We’ve had gameplay mods for SF4 PC version for a while now:
I’m surprised noone’s attempted a ST-ish mod for it. Strip out all the non SF2 characters, remove ultras, FA, dashing, EX moves. Try and tweak the physics and speed to match ST. Try to get framedata somewhat close to ST, considering the differences between 3D animation and 2D animation, etc.
It won’t be exactly the same, but you should be able to get pretty close, depending on just how moddable SF4 is. Maybe you don’t have that much control over everything, dunno.