The wood will be very nice and I agree with you in that it would be a shame, if not a sin, to cover it with a patch box. Honestly, I've never used a patch box to hold or carry anything....but they shore are purty on some rifles.
I'm not the best person to ask about what's period correct regarding lock styles. It isn't that I don't care, it's that I don't know!!!!! Just briefly checking it appears that a Manton & Ashmore lock by L & R, a lock I like better than the Siler, or a Ketland late era lock would be correct. They aren't too dissimilar in appearance and personally I like the rain proof pan of both. Run those two locks by the folks who know those things and see what their response is. I'm kinda curious myself.
I've owned several 50's over the years and to the best of my recollection all of them would digest 90 grs. of either Ffg or Fffg with equal aplomb, given the right patch/ball combination. With the 7/8 barrel I'd probably try to make Ffg work simply because it operates at lower pressure. Velocity will most likely be lower than a Fffg load but will certainly be adequate. 90 grs. was also my hunting load and any deer-sized game within reasonable shooting distance was meat on the table. I have no knowledge of what a max load would be in that particular barrel. I've never needed a max load in any handgun or rifle I've owned, smokeless or black. My experience is that max loads aren't necessary, are almost never the best balanced load, consume more powder than necessary to achieve the desired result and cause undue and unecessary stress on the firearm......and sometimes the shooter! A max load can sometimes be the most accurate load but just as often is difficult to make accurate. As with all firearms there is never an "always" or "never" when it comes to shooting and loading them. I don't believe I'd get too hung up on max loads. I'd try to achieve the best balanced, or optimum load.
Vic
