Chevy made vortec engines since 1992 first with the cpi injected that went to 1994 engine code W L35 262Cu. in with balancer shaft.
But they also made 4.3 V6 Z code LB4 262Cu. in carburated
Then in 1995 they made vortec W code but with Tbi up till I believe 2004
No, you can not interchange the fuel injection systems because of computer differences, also some vortec heads have the intake manafold bolts are on angles and some are straight up and down.
The W code Cpi has 195 hp, and the Z has 160 hp
there are very few upgrdes for the W code Cpi