Magnum 360 rebuild help

If you don't know the history of the engine, and did not get to hear it run, I would suggest you should check all the rod bearings. You'll need to install a car style oil pan and pickup anyway, so they'll be accessible. Many of these have no problems in the shortblock components, but if it has a problem why not catch it now. I have had a few of these apart that had one rod bearing and crank journal torn up. You don't want to find that after getting it all installed.
Once you are sure it's all good, go for the camshaft upgrade and matching valve springs. You can keep the factory roller lifters, but factory valve springs definitely won't work well with a camshaft upgrade.