vector,
if i were a betting man, i would say your engine is a 65 230. it has the correct valve cover and motor mounts for the application. the dist is from the mid 70's and was probably put on for less maintenance.
250 cranks are easy to get, just order whatever piston you need new or use 307 sbc pistons off the shelf. tom

Inliner Member 1716
65 Chevelle Wagon and 41 Hudson Pickup
Information and parts www.12bolt.com