This is the old Ford vs Chevy Question.
I like the cross pin because it is easier for me to remove the cylinder when cleaning.
The black powder frame is more authentic for the time period of CAS
44-40 vs 45 Colt
If your going with black powder go stright to the 44-40 (44 WCF) as it seals the chamber better and reduces blowback.
IMHO If you are going to use smokless go with the 45 Colt; the brass, as least for me, is easier to reload I get less crushed cases in my progressive loader
Reduced loads in 45 Colt will produce more blowback in rifles then the reduced loads in 44WCF
Of course your can add grits, or other fillers to help reduce the 45 colt blowback
Either one will make a great CAS handgun