Spent a little time in the shop and tried the gun with the bolt removed as suggested.
There was no difference at all. It looks very much like the hand is jamming up against part of the ratchet.
I tried it with original BP cylinder and it rotated and cocked fine. So it is somehow related to how the hand is interacting with the new cylinder ratchet.
I also tried it with and without the loading ring in place with no difference.
I have slowly worked the hammer pin on a new hand/spring so it fits the hammer, I now need to begin honing down the new hand where it engages the ratchet. Not sure how to begin other than make it close to the original and go from there.