as old said.
if it bolts up.. yeah.. 'probably' fine.
here are the issues you have to look at.
there are 2 5/16 and 2 3/8 spaced studs on carbs.
you have original manifolds made for each size.. and then universal manifolds made for both.
Some have even takent he small manifold and filed out the ears to put the large carb on.
as long as the engine in the 631 ( 134ci ) has not been swapped for a 172 CI with associated manifolds and such.. IE.. should be fine if it bolts.
And yeah. you can run a 172 on a 134 carb and be derated..
find out what carb you have.. and that will tell you the mount size. match up that mount spacing, and then get a carb in that mount spacing for the CI of your engine. which, again, if original.. is 134ci.
and yeah. I have seen lots of stuff swapped.
I have a 950 wearing the small manifold of a 134ci engine..a naa and it's wearing it's carb too! ( it's what i had on hand.. and the 950's carb was shot and manifold broke... )