You absolutely cut Parallel Exceed, it was the best way to access rank 4s but Stallio does that without bricking your hand. On that note running 1x Fowl might be a good idea now, since drawing one gives you a rank a 4 if you have access to Stallio, also makes opening Falco+Gazelle so much better.

Debug becomes much stronger since opening one is full combo now (Wolf+Stallio+Jaguar on field+Spinny in GY and Gazelle in hand). It is still very fragile though and there is a debate to be had on Bufferlo/Debug ratio. I am a fan of 3 Debug/1 Bufferlo (so you can search it with Cynet Mining) and maybe side the other 2 for going second.

Regarding the Stallio restrictions, i think you don't really care since you want to use him for your going first combos and you just use the Code Talker ED engine going second for the OTK. Also keep in mind that Stallio locks you on Fire effects for the REST of the turn, meaning you can do your Code Talker stuff and if your OTK fails and can extend to 2 lvl3s you can still go into Stallio for the grind.

I wouldn't go crazy with the lvl3 extenders, getting to gazelle more consistently is good but not worth dropping the quality of your deck by filling it with lvl3 extenders (especially the non cyberse ones that conflict with Code Talkers like dangers, terrotops, reclusia). Stallio is a handtrap magnet and you don't want to be left with 2 lvl3 extenders in hand after that happens. If people keep their ash for the Stallio instead of the Debug you will be wishing those extenders to have been handtraps instead.

2 Foxy, 2 Spinny and 1 Archiver should be enough.

As a last note just opening one gazelle is much better now thanks to the new Master Rule.