Without actually seeing the guns, it's hard to be sure of what they actually are. Odds are, the ones chambered for 7.62x39mm are SKS rifles, probably made in Yugoslavia, as BigBill pointed out. The ones chambered for 7.62x54R are probably Mosin-Nagants (especially if they are bolt actions). Of those, the long ones are probably 91/30s (unless they're really long, in which case they're M1891s) and the short ones are M38s or 91/59s if they have no bayonet or M44s if they have a side folding bayonet. Those are best guesses.
7.62x39mm is right around .30-30 as far as ballistics goes. 7.62x54R is closer to .308 Winchester, but falls a hair short of it if I recall correctly.
Now, there is a remote (very remote) chance that some of those 7.62x54R guns are 1907 carbines or Czech 91/38 carbines. If that turns out to be the case, buy them all. Probably, they aren't, but it never hurts to check. Even if they're M44s that a cruffler (C&R FFL holder) can get for $50-$60, $80 wouldn't be bad for them since they'd probably cost about $10 to ship and anywhere from $10 on up to transfer if you don't have a C&R.