hey there, im new to the forum and was looking for some help. i was helping my friend move some stuff recently and saw he had some pretty old bikes. i have been looking for some sort of fixer-upper project and thought this was perfect. the bike in question is an old schwinn racer.

i plan on converting it to a fixed gear and am now in the process of sanding it down. the fork and headset are in fine condition as well as the bottom bracket however i would prefer a new bb rather than than the 1 piece. my question is how do i figure out what bottom bracket will fit in this bike cause it looks like a pretty big hole. i did some research on other forums and came across this


which someone else used on an old bike. my question is how does this work and will it work for my bike? im sure im gonna come back with more questions but thank you for any help you can give