Swap in a used 96 to 2000 350 vortec engine. factory roller cam and votec heads. These engine are cheap at engine salvage stores and will bolt right in using your current throttle body injection.
If the vortec swap isn't enough then add some bolt ons. (headers, rv cam, intake, better efi tune, etc...). Should be able to make 350hp and close to 400 ftlbs of torque and while retaining a good idle and low speed torque.
Could also do a top end vortec swap but not as good due to the flat tappet cam.
Some how, get rid of those 92 heads.