Performer RPM Cylinder Heads For S/B Chrysler

saskatchewan said
I had not thought about swapping transmissions, but, that could be an option. I checked out the Hot Rod blog and there is a description of what is involved in taking one of the Dakota trans and putting them in a earlier model Mopar.
Mopar Overdrive Transmission Swap - How To - Hot Rod Magazine

Since the car had optional manual transmission, would there be any 5 speeds that would fit?

As for dual exhaust and 4bbl, I would always do the two simultaneously. How much you can "flow in" depends on how much can "flow out". Once I put a 4bbl on a /6 and there was an ENORMOUS improvement in power and drive ability, however, I later installed dual exhaust and there was another noticeable improvement in power.

Five-speed manuals are big money. BIG BIG money.
There is a guy here on FABO who is experimenting with fabbing up a kit to install an AISEN in a SBM, which would easily handle your 273, or even a 318.....but I forget his name and the title of his thread.There were 2 ratio sets available in the Aisen, and you would need the closer ratio set. You'll have to do a search.

I found it!
6 Speed Slant Six
Scroll down to the final post.
He built this for a slanty, but I seem to recall him saying something about fabbing up an adapter for the SBM, send him a PM if interested.