I had built a Sherman Oakes copy of a Bob Bogan scaled down copy of a Watson chassis, with Bob doing some updates himself; It had a stock-displacement single-cam Honda CB750-F with Weber DCOE 40 carbs and Acro running gear. Life got in the way and I never finished it. Carl Nigh actually bought most of the Acro stuff and brought it out here to Indiana to sell it. But for over 10 years I crewed for Jack Zimmerman out of Oak View, CA; his TQ's always had CB750-K's punched out to 836, Hilborn injection, Schneider v-drive, Mallory mag, Carillo Rods and I think Wiseco pistons. That was pretty much the hot setup back then as now, although when we started there were still a few Crosleys, Triumph twins and triples, a couple of Fiats and even a guy who ran a half-VW, if I remember right he tried both 2-cylinder opposed and left-bank-only. Later on some twin-cam 750 Suzukis and Kawasakis came on the scene. Terry Farrar experimented with a Harley with a single-stack Hilborn, and CRA Sprint Car shoe and TQ chassis builder Bob Meli even tried a 3-cylinder Chevy Sprint, but the single-stick CB750 still ruled the roost. When USAC took over the sanctioning from the NMRA and CMA groups and loosened up the rules a bit one car showed up with a CB750 mounted transversely with chain drive (no trans, though) and there were a couple of guys who tried 2-stroke power with CVT belt drives, most notably a fellow by the name of Andy Bondio, who's done pretty well with some radical equipment at some obscure event in Oklahoma
Another interesting side note is that for a number of those years one of the other guys on Jack's crew was Dean Buckley, the father of Sean "Jackslash" Buckley. It's a small world...