All of these boats are nearing 40+ years old. Finding a hull that doesn't need any rebuilding is nearly impossible. It has a good start on a pump (might need rebuilding). The first thing I would look at is the bottom, checking for a hook/rocker. Remember, these boats have had a big block sitting in them for nearly 40 years. Nothing like a 600+ lb. paperweight to push the bottom out of shape.
If the hook/rocker minimal, repair the floor, find/build a power plant for it, and find a deal on the interior. Nothing wrong with a 1/4 stringer boat, as long as its solid. Starting with a bare hull, at least you know what you've done to it, not paying top dollar for a float that lasts a weekend and THEN needs a motor, steering is tight, seats are loose, etc.
I'm on my 5th boat now, and only my first one had a running BBC (10/99). It lasted about 6 months, and lost a piston and block. I've built my own motors and pumps since then. Boats are built, not bought.
As far as power plants- I'd go with an LS first, then SBC, BBC, and BBF last (only because I have SBC/BBC parts) all depends on your wallet, and goals.
thats all I got...
Dan'l