Waking Up a Turd

Please don't take this the wrong way as I am just thinking out loud trying to help. If my budget was really tight, I would probably just swap in a 5.9 with a regrind cam for now. Build your other engine the way you want as funds allow. You can always sell the 5.9 when your new motor is built and get your money back out of it.
I like this route. Iā€™m doing it myself right now. The ā€˜00-5.9 in my ā€˜79 B body is in excellent shape. (Only 80K)
I added headers into 2-1/2 exhaust, a RPM intake and 600 carb, upgraded the ignition to start. I went to Hughes for a spring package to allow for a better cam in which I have not bought yet. The trans is a 2400 stalled 727 with 3.55ā€™s out back on 26-1/2 tires.

Without the cam... this is a really nice package. An excellent driver with really nice (but still modest) power.