My solution was similar to Drgbike's. I used 2 629-1 guns to get mine. Bought a 4" and a 5" 45 acp barrels and reamed the 44 mag cylinders to 45 colt. Fit the barrels, which must have the barrel extension trimmed to clearance the longer 44 mag cylinders (same length as factory 45 colt cylinders). Also have to recut the forcing cone. On the 4" gun I cut the back of the cylinder for moon clips and it fires colts, acps and 45 win mags. The barrels I got only say 45 caliber anyway. I picked up one of the 629-1s for $500 and the other for $550. Barrels were around a $100 each and I already owned the reamer which is about $125 new, but you can rent one for $35 from
45 Colt (Long Colt) - 4D Reamer Rentals
Nope they are not collectable anymore, but they are very shootable.