In my opinion, 8 x 32 will be lots strong enough for all the screws, but there is lots of room for a 10 x 32 screw in the rear of the plate's bolster. When I use two #8 screws for the lock, I always mark the rear one with one file cut across the shank, and two cuts on the forward one. I do the same with the rod pipes, so I can remember which goes into which inlet, and which end is 'fore and which is aft'. I got the idea from studying a Brown Bess that had reference cuts in all the parts, to differentiate them from the next gun on the bench, I suppose.