The whiplash and thumper type cams have been proven to work. I have 2 and it isnt just for idle chop. They build cylinder pressure in engines that are needing it and wake them up very nicely. Night and day difference in low end with all other things being the same. Change valve springs to meet the cam. More converter made both nicer. Nothing radical, 2500-3000 would be plenty.
People get stuck on thinking these are only for the ilde and just a gimmick. Couldn't be further from the truth.
Now if there was going to be a complete rebuild, then build some compression and go with a more traditional cam set up and be much happier overall. If not rebuilding, it is likely the best choice for the setup.