You can achieve some power gains w/the 20r head on the 22r, but wont likely see any of it w/33's(or 35's), and 4.30's. Your cheapest performance gain would be to swap a 5-spd for the 4-spd, then regear w/5.29's, so you can run 35's when the time comes.

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed