318 budget build help?

In terms of old affordable Mopars - don't overlook the F bodies (Aspen and Volarie) as they came with 318s and actually ahndle and stop well given their age. Some had 360's too. They are very inexpensive, pretty much all the cheap speed parts fit them, and the repair parts aren;t really expensive if they need something. Another route would be the 80s vintage Dodge trucks that came with v8s. A shortbed 318 2bbl will respond very well to mods too and is very easy to work on and repair.
If you can scratch up a couple grand that would buy something decent in either of those lines.