Depends.. If it is a diaphragm carb, you need that one.. If it's a float bowl carb, you need the one for the bowl carb.. If it's a prejet, you can pretty much run either bowl rebuild set.. But if it's adjutsable, you need the one for the small adjustable bowl carb.. The kit should say which sizes and models it will fit.. Most likely being a 2.5 it's the od school, fully adjustable, bowl carb..
H20 22 25 30 35... Hs40 50... H 40 50 60 70 should all work...
I guess the cheap rebuild kits, the main jet adjustment needle is threaded all the way to the head, so the needle leaks fuel.. :facepalm: So you'll wanna use the original screw, unless it's rusted all to hell.. 1/2 rusted I'd still use it.. :laugh:
any pics of the carb?