This should really be in the drivetrain upgrades section, that is where all the V8 guys look. Do a search of that section for headers and you should find a mountain of info.
Also, take a look in the Information Section of the main site here. The engine swap article is the big one:
http://www.luvtruck.com/pdf/engswap.pdf
It will have a lot of what you are looking for. I think in general, most SBC swappers use Hooker headers, but I think a lot of block huggers work. It does depend on the mounts you decide to go with too. If you torch all the stock mounts off and use a front engine plate you could probably fit a few different options in there better. You could also change the front suspension to a coil over setup and get the torsion bars out of the way for more room.