Fred, your list would be really helpful. It will undoubtedly save a couple of trips to my FLAPS.
Definitely going with a crate motor, either the 260Hp or the L31. Thanks to everyone's input. What are your thoughts on finding a good used T-10 or M-20? My concern is that many of these were original to muscle cars and might have been thrashed pretty hard but it is hard to swallow the cost of a new trans.
Also, the HD clutch in my '56 has less than 1000 miles (235 and SM420). Could/should I reuse it with the new engine and trans? Don't want to go cheap if it causes problems down the road but there's a lot of life left in the existing clutch.