Very interesting and quite good looking too. Should work just fine. I would restrict myself to 3 drams of 2F with a patched .690" ball. The pressure
generated should be less than an 1-1/8 of shot and 3 drams (82gr.) powder. This load should develop around 1,225fps.
Like on the Pedersoli doubles, the nipples are really high and thus the hammers do not fall around the fences as they should. This renders the fences
cosmetic only, not of any value - which is a poor design.
If I may suggest, remove a lock and allow the hammer to fall another .150", maybe .2" and see if the main spring bends down below the lock plate.
Allowing this much fall will show if you can reduce the height of the nipples, to allow the crook of the hammer to fall over the fence. If the hammer cup
is not below the top edge of the fence, the fence is not doing what it is meant to do- that is, protect your big shiny eyeball from cap fragments.
Correcting this make the gun safer for you to fire, if you are so inclined as seems by your note of getting a .690" mould. both Lee and Lyman make a
.690" RB single cavity mould.
This is my Pedersoli before and after working on the nipples. I was able to reduce the height of the nipples, thus allowing the hammer cups to curl over the fences.
This top picture was taken with replacement nipples from Track, that were slightly shorter than the Italian nipples thus, show almost good enough curl, but not quite.