Dont know if this is correct board but a were taking the air pump and emissions off a friends 305 tpi motor and i was wondering what is the size of the shorter belt needed? What else is needed? Thanks

 

look on the tech articles part or this link should take you:
https://www.thirdgen.org/serpentine
it will tell you everything you need to know and the setup of the belt...
good luck and post how it works out...i will be doing this probably this weekend when i get my headers back......