As for the questions posted....
I would buy one specifically for a 500 series, but I'm trying to be thrifty about this. (read: I'm being cheap b/c I just need something to putz around with) This is all mostly a "what if" question anyway. If I should get lucky enough to snag this set of wood for my pre-budgeted amount
+ shipping, I'll be glad. At best I get a set of wood stocks. At worst, I pass it along to someone else that can use it.
As for LOP, a standard stock won't fit me under the best of circumstances, I'm 6'5 and closer to 325 than I want to admit... I also have the ape-ish long arms to match...