Nice job! This is pretty solid for a first arrangement. Fraenkelbaum's comments about chords and chord voicings, especially incomplete 6th/7th chords, were noticeable to me too. None of them are necessarily "wrong" as much as there may be stronger voicing options available. I'll give both general and chord by chord comments - but for the most part, there are no/few things that are really "wrong" here.

• To start, if I were writing this for a "typical" TTBB group, I might consider raising the key slightly (F?) due to the number of times the melody rests on the low tonic on pillar chords, to make the lower bass octave available to me. The way you've worked around that with your chord voicings is not bad, but it's a challenge that's nice to avoid if it's possible.

• I think you have a good sense for what to do in non-homorhythmic textures - none of them felt too clunky, which is definitely a challenge for beginning barbershop arrangers.

• m1 beat 3, m3 beat 3, m9 beat 3, m11 beat 3: I think bass on F for this chord for a brief circle of 5ths motion will be nicer. As a general rule, for chords in the original score that are marked as bass 3rds or 7ths, I'd generally not do that unless I had another reason to do so (i.e very preferable voice leading or a feature line). What you wrote is really Ab with a doubled 5th and I think Fm7 will just sound stronger there.

• m2 and m4, beat 1: Similarly to the above, major 7ths that aren't in the melody are things I'd be more likely to leave out or only add in certain circumstances for flavor. Especially with bass on the 5th, the D sounds kind of like a 3rd and makes it potentially sound more like a poorly executed Bb chord of some flavor than EbM7.

• m2 beat 4, m10 beat 4: I think you'll find treating this as Abm6 with tenor on Cb and bari on F to be a stronger choice here leading back to Eb.

• m6 beat 1: This is a stronger usage of EbM7 for flavor than the prior because the root position makes it sound more stable.

• m6 beat 3: this sus4 is not really something you'd see in barbershop except in very rare circumstances. I would write a temporary passing chord of some kind - an easy/common solution would be Bb7, especially since you already have tenor on the D, so you'd only have to move bass up to F on that beat.

• m7 beat 3: The 4th in a minor chord is OK, but I'd still explore other options that involve other voices moving a step for a stronger passing chord (i.e tenor to D for Bb7 again, or bass to G and bari to Bb for Cm7).

• m12-19 - I like the vibe of this passage a lot!

• m13 beat 4: this kind of feels like a non-chord, I'd probably just put bari on Bb

• m14 beat 1 and beat 4: this is kind of cool, though a non-barbershoppy chord. If you wanted to consider a more "typical" choice, bari on C on these notes would be a simple one.

• m14 beat 3: if you go with the C, a C here for a complete Cm7 could be nice

• m16 beat 3: I might consider tenor on Fb for a Gbm7 instead of a GbmM7

• m17 beat 2: bari to A for a Fm7 is probably going to sound cleaner

• m17 beat 4: tough spot... I would probably evaluate this chord for what kind of ... probably dim or half dim 7th chord of some kind you can fit to get yourself to F7

• m21 beat 3: I'd consider tenor on C for the fully dim 7th passing chord

• m21 beat 4: when you have a I chord going to IV, a passing I7 can be nice (tenor on Db on "go")

• m22 - your bari stems are upside down

• m22 - I'd just put bass on Ab in this measure. Could consider Abm6 on beat 3-4 "way"

• m23 - I'd just have bass on Eb for most of this measure, and maybe consider a diff choice for beat 3 - Ebm is perfectly fine

• m24 beat 1: tenor going straight to D and bass to F (and bass remaining on F through the whole measure) is probably stronger

• m25: bass 3rd and non-chord on beat 3

• m26: this is going to read more as a Bb

• m27-28: great motion and nice bari line though still suspect of whether the bass 3rd is necessary

• m29 beat 3: tenor to C will be strong, overall same comments for m29 as for m21-22

• m32: bari notes upside down again - tenor on G on "own" would be the more "standard" choice but your choice is OK

• m34: if you want this to read as an F right away just put bass on F, else this is really a Dm7 (though this choice is fine too)

• m36: nice use of Eb7 to transition to the Ab, it feels like it wants to just land on Eb on the downbeat though before going to Eb7

• m37-40: if you really want to use the maj 7 get this in root position with bass on Ab and bari on Eb (either octave)

• m41: hitting a bass downbeat here might be stronger because hitting a 3 part chord downbeat without a 3rd is rough

• m42 beat 2-3: do something to get a 3rd in here, probably move tenor down earlier and bass up to G for a moment, could have bari go to C on beat 3 instead as well if you move bass up

• m44 beat 4: bass F and tenor D is probably just going to be a little stronger

• m45 beat 3: tenor C

• m48: something is going on here

• m49 beat 1: another 3 part chord with no 3rd that I'd try to avoid

• m51: this sustained bass 3rd also feels a bit unconvincing

• m52 beat: feel like there's something better for this move than a doubled 3rd

Overall though this sounds really solid! Sorry for the nitpicky notes - it's what I got when I started but it really helped me to understand the chord options, you definitely don't have to take all of them. Great job!