I installed a 250 and auto in my 53-3/4t, I used the factory mounts from a 69 1/2t then welded tabs on the frame to connect to. I had to build a crossmember for the trans, and removed the original bell housing crossmember. I used a footfeed and cable from an 80's Chevy. I'd say your vacuum portal could be placed anyplace around the carb base,,, I assume you need this for the wipers, power brakes etc. Keep on trukin'
