From Santa Cruz CA  now livin in northern IN 
You probably should move up to a 22r if you can find one
Or run a 20 r also , or take your 20 r head and bolt it  up to a wary 22r block
Any way all these will bolt up and run , u just need the right distributor on the same head
Meaning " 20 r head 20 r distribrutor 22r 22r distributor " so it just bolts in to the tranny and frame
All the elctronics work just fine .... The only thing you want to keep is your alternator
This gets reused!!    I have the same truck !! Good luck