When I was interested in b/p I reseached the issue of what is the best revolver and it seems that the Ruger Old Army .45 (NOT .44, this is important for your FAC slot) is by far the best design/engineering choice as it is essentially a modern design, plus it is made of stainless steel. It is very accurate, nice trigger (after a bit of tweaking) and clear sights, and has alot of oomph so you can shoot it at 50 yards.
However, it is not eligible for most competitions apart from the 'free' class so that is something to watch out for.
The .36s are a bit disappointing, they don't produce quite the same blast of sparks and burning wadding and a decent size boom. If they fireworks aren't there you might as well buy a nice airpistol instead methinks, as most of your time as a blackpowder shooter will be spent cleaning and loading your gun you want to get as much fun per 'bang' as possible IMHO.