If your original Trooper is a .357 "I" frame a Python cylinder "can" be used.
The original Trooper is either a .22 or .38 Special "E" frame, or a .38 Special or .357 Magnum "I" frame.
The "E" frame has a firing pin on the hammer.
The "I" frame has the firing pin inside the frame.
Note that these are totally different guns then the later Mark III, Mark V, and King Cobra models.
Note that cylinders require fitting and adjusting, they don't drop in.
Cylinder work requires a real pistolsmith expert who knows cylinder work.
A used cylinder assembly may not fit because cylinders are fitted by first trimming the rear face of the ejector to set head space. Everything else bases off that.
Used ejectors may already be too short to use because of being fitted to a different frame.
Just because a cylinder will snap into the frame is no indication it actually fits or is even safe to fire.
Properly installed a cylinder assembly needs to be adjusted and checked for...
Head space.
Barrel-cylinder gap.
End shake.
Chamber-bore alignment on all chambers.
Timing on all chambers.