A lot of the "sporterized" ones have been rebarreled for .308. And if it's been rebarreled or a new bolt put in (or even if not) they often have headspace problems because the locking lugs are at the rear of the bolt.
And there are fake No. 5 jungle carbines making the rounds out there too. If you go with a good quality No. 4 that would probably be your best bet. But have a gunsmith check it out.
I collect .303s (have 5) and shoot them all (I keep no cats that catch no mice), but I find it best to reload for my best one (the Long Branch sniper rifle) and head size the brass only. Much more accurate that way (if a tad more difficult to extract).
Best way to get a Garand is join your local shooting club and participate in a qualifying .22 LR match to get into the Civilian Marksmanship Program. We got a very nice Garand still in the Cosmoline through the CMP, and the price is just nominal because they are distributing surplus from the govt.