Buddy has a complete 400, carb to pan. Runs well, good compression on all cyls. The bell housing is different for your motor but he has that as well so you can bolt it right up to your 4spd. PM me if you are interested.
Have you tried jetting down your carb? At this altitude you can use smaller jets and get the same performance. It might not be smoke blowing out your tailpipe but instead unburnt fuel. I had the same problem with two of my trucks. If your plugs are all black and sooty then you probably could use smaller jets.
Hey If you haven't bought another engine-I was thinking about buying this '65 4x4 F100 in Denver that has a 400 in it. I don't really want a 400 and would consider buying it and then selling the motor to you. I could use a 352 or 300 instead. I don't need a 400 double barrel carb stomp machine.