I found this article on Automotive.com, though it’s really an article from JP Magazine.  The article highlights improving performance on a variety of Jeep engines.  Here’s two excerpts and a great pic.

“Dual carburetor manifolds in the ’50s were available for just about any engine you could imagine and an old-time company, Burns, made a log-type manifold that utilized two Stromberg Ford V-8 carburetors for the Jeep four-cylinder. I’m sure these helped the four-cylinder flathead’s performance, but, still, the long-stroke 134.2ci engine needed a lot more than this…”

And a little on the F-head

“The next step was to swap in a later model F-head engine. It wasn’t technically an engine swap because it was a direct bolt in. Still the same basic engine, but a new cylinder head design with the intake valves upstairs in the head instead of the block. Depending on the compression ratio, which ranged from 6.9 to 7.8 (depending on year and usage), it was rated at 72 to 75 horsepower at around 4,000 rpm and torque was up to 114lb-ft. This one got a balance job, some performance pistons from Speed-O-Motive, and a Holley carb from a Falcon six. My new performance motor maybe made 100 horsepower on a good, damp day.

Harry Buschert, who owned a farm implement repair shop in Hemet, California, was a real innovator in design. He built up a very-modified, four-cylinder F-head that even had a Paxton Blower that he had salvaged off a Packard….”