From recent builds locally, as well as a lot of YouToobin' I've been up to with this stupid cold...I would unfortunately suggest an LS-swap, unless you already have a lot of the pieces you need for the SBC. Figure you'll be $3k into a decent CL/eBay Chevy 350/383 build, with a lot of work...and you'll be happy if you're pushing 400-425hp. LS swap will ensure power, reliability, and some economy with the guarantee of aftermarket parts for the next 25 years.
If there's no tranny in your roller, even more reason to get an LS/4L60 take out from a dismantler. Start from there and use bolt-ons as your budget affords to build power.
How is the fuel system set up? Electric pump-in-tank? If you're looking to keep it as simple, carb'd as you can get it just to do some track days, go cruising, and have fun without throwing a bunch of dough at it, just get a 383 stroker (if possible) that someone's getting rid of.