welcome to the garage, Tim - pull up a running board and check out the search feature here for info on clipping either series, lotsa discussions and opinions been bandied about over the last year - not something I consider worth the effort or $$$ to attain a good driver
the 56 can take a small block and modern auto trans w/ very little change - nearly a bolt in, and the suspension can be fiddled a bit w/o a clip - disc brake kits are available to go on the stock spindles, and power steering might be possible too, but w/ the stock steering wheel, the right size radials, and the front end in A1 shape, they're not hard to steer
we'd enjoy seein some pics of your rides, and keep us posted on your progress
Bill