Converting 66 stepvan to automatic

[yoderconsult]

Well..here's one for the books..my wife said she couldn't part with the 1966 Shorty Chevy Stepvan I had for sale in the classifieds...and wants to go ahead with setting it up for festival catering....cool!!

I want to convert it from the 3 on the tree to an automatic. I dont want to spend a fortune, but I also want it to be just as reliable as it is now and not lose to0 much power (It is low geared now and weighs 4,000 lbs). It has a 6 cylinder engine that I believe is a 235 chevy? (Any quick way to tell?) The prior owner if I recall said it was a replacement engine from a slightly newer car. The tranny is original as is the driveline and rearend. Any wisdom greatly appreciated.

Love vintage metal. Now if I can just talk her into a sixties pickup.....