On Colts, the Triggerguard and Backstrap are fitted to the frame at the time of assembly, so there's a lot of minute differences - and that's on the "real" Single Action Armies.
The Colt 1860 Army Triggerguard and Backstrap can be fitted to the frame if you need to.
You may find that it suits your grip.
As to the Bisley - I don't like the feel of that grip at all, since it puts my wrist into an uncomfortable shooting position - but that's me.
Some guys swear by that style of grip.
I'd swear at it...
Alternatively, you can look at different grips, to see how they feel.
Scouts Out!