Welcome aboard, Ron!
Yes, it has been done. There was a one off STC for the O-235 re-engine, but it was never offered to the public, to my knowledge. There is no market for it, as the cost for the minimum HP gained is prohibitive. It probably made sense to someone who had a spare O-235, and an engineless 150.
Yes, there is a class of experimental racers that use modified, suped-up, O-200's. They're high on performance, but low on durability, just like NASCAR. They run custom mixed racing fuel to handle the higher compressions, and custom propellors to handle the power and deliver the speed. Pistons are one-off forgings, machined to fit, and cylinder heads, crankcase, camshaft, crankshaft, induction, and exhaust have all been modified, just to name a few. To do this, you would have to register your 150 as experimental, with the only advantage being the ability to spend extremely large sums of money just to devalue your airplane. The only thing in this category that makes sense (for some) is a 150hp Lycoming O-320 or 180hp O-360 STC'd conversion. There are several owners of "150/150's" and I think "180/150's" in the club.
Little concern for TBO? NASCAR takes a basic 180,000 mile engine and turns it into a rip snortin', asphalt rippin' 500 mile engine. Lets see, similar performance in an O-200? 5 hour TBO! If you're lucky!
Carl
