I was thinking on those 302 fords. If the crank journals are at 90* relative to each other, it could quite easily be made to run on four cyls. Although the four cyls engines I've worked with had flat cranks with journals at 180* out from each other. I don't know ford firing order of the top of my head, (I know six cyl continental order though ((too young, too old, just right)) 16 54 32) but I suppose there was a reason they were used. To keep the engine balanced somewhat. No matter what, with that amount of rotating mass it would get shaky. The cam could stay the same, being that it still needs intake and exhaust strokes. The intake manifold might get interesting, but could be done. The exhaust on the compressor side might need to be a one-off custom, but it wouldn't get as hot so tighter seals could be achieved. I like this.

Scrappin ain't easy.