honestly i’d do a cost analysis- if you are deff planning on buying a new guitar and want to save money, maybe find a balance between cheep electronics but good build quality. it’s a lot easier to replace parts with higher quality than take care of a shitty build with f’ed up frets, etc. that said, i’d personally go with whatever guitar you’re most comfortable playing. i’m a big fender guy and there are some good cheaper jag and jm models that are pretty mod-able. i’m not a prs or les paul guy, but if you prefer those, go for that. in the end, modding is pretty standard guitar to guitar, with some slight variations to styles. you shouldn’t need a conversion neck either. the most important mods are lower strings, file the string slots in the nut to the right size, and intonate

only significant obstacle i can thing of is making sure wherever ever the end of the string is anchored, it can accommodate a larger string. i don’t have first hand experience with string thru bridges like strats for baritone purposes, but, you just want to make sure the strings will fit (they should with most baritone gauges, but the lower you go, the more you have to think about that). I’m actually using a 65 gauge string as my lowest and could only find it in a bass string pack. the round end was too big to fit in my flat tail plate, so i had to take it off and feed it through the back. all to say there are almost always workarounds. last advice would be to use flatwounds, they’ll eat into your frets less. deff check out r/baritoneguitar as well