I have a question, I have an 89 L98 and was thinking about replace the engine. I have a sbc 383 and a sbc 406 sitting in my garage. Could I swap in either one of those engines into my 89 and make it work...? Can I use the all l98 set-up except the block..? Any help or comments greatly appreciated.

 

The ECM would have to have a new chip burned for the increased displacement, and larger injectors (assuming your HP goals require them). The next problem would be the L98 intake manifold. It is barely adequate for the 350ci displacement of the L98. Per the GM published HP and torque curves, it has great low end torque, but falls off quickly above 3,500 RPM, running out of steam at 4,500 RPM. Putting that intake on a 383 or a 406 would seem to be a significant mismatch.