NO, they are not interchangeable. The SFX has a longer barrel, so at a minimum you would have to swap the entire upper assembly (slide, barrel, recoil spring) and that is only if the frames and trigger groups are identical designs.
Either they share the same frame/trigger group or they do not. That is not something that should be verified by "function testing", but by actually verifying the design/specs. Function testing a firearm in an unverified configuration could do a lot worse that just be unreliable, it could do damage to the parts, the shooter, and bystanders.