89 chevy blazer conversion?

I have a 1989 Chevrolet S-10 Blazer with a 4.3 liter V6 motor with the stock TBI system. I would like to change it over to a Multi port fuel injection system but i am concerned that i will need different cylinder heads. I know the intake manifold will have to be changed to accomodate the rail injection system and that a new ECM will be needed but if i have to change the heads i dont even want to mess with it, Any insight will be helpful thanks alot.=)