The answer is maybe.... maybe it's as easy as dropping it in or maybe it's harder like dremelling a bit or maybe it's even harder in that it won't fit period.
As for getting it fixed. Yeah it might be a good idea to hold onto it for a year. Worst case you sell it to someone as a parts gun, best case you find a lower that fits and everything is good.
Getting a lower will be kind of hard. You can find them in Canada but they're not really common and most of the ones I've seen are in the AV only section of this website. I think that's all I can really say about it other than expect to pay between $150-250+ for a lower depending on plastic or metal, type of matal (zinc vs zinc alloy vs alu/steel, vs CNC'ed alu/steel), and such.
PS: Maybe you should ask your friend to pay all or part of the repair cost....
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE