just trying to finish up doing the same thing.
all the advice given before is on the money. i chose the 700r4 and an early c10 rear end with 344 gears. there is some fabrication needed(linkage/foot starter/remove existing tranny mount reroute brake lines and mabey exaust) and a little more.
any way these link might help with some of the parts.
adapter plate. not cheap but fits like a glove.
http://www.transmissionadapters.com/
new mounts. bolted rite on.
http://www.scribd.com/full/9744366?access_key=key-2jisr1kyee11tc4b2rh6
look at page 75 and 76 all the mounts you need should be on those two pages.
good luck
Dad

54Daddy

http://s646.photobucket.com/albums/uu184/54dad/