How about what was used in the GM Jimmy 671 2 stroker (6 cylinder 71 cu in per cylinder), very popular at the time...I think city busses used them en-mass. Lots of "rock buckets running them on bobtails with 10 on the floor. An experienced driver could make those suckers play some sweet music.......had oil leaking problems as I recall.
Recollecting the fuel-air inlets and exhaust ports were in the center of the block and the pistons were on either end (opposed) attached to the same lobe on the crank (I think) so you got suck and blow simultaneously with one rev of the crankshaft. Don't quote me on any of this except the music part.