So I just bought a Remington 870 wingmaster in 12 gauge and the dealer said that it needed just a couple of parts. I decided to pick it up for 140 dollars since it was in very good condition. When I disassembled it, I noticed it was missing the firing pin spring and the locking block. It's a 1974 wingmaster that shoots 12 gauge. I've looked online and I've seen oversized locking blocks, or old style locking blocks, and is it okay if I put a 20 gauge locking block in it? BTW it's not a magnum and it only accepts 2.75 inch shells.