RE: Best 45/46 for warbird racing?
If you can use the jett or ultra-thrust muffler.... just about any of the engines out there are fair game.
The OS46AX loves the tuned muffler. And it has some bit of torque - 9x8, 9x9 - if need by 10x6, 10x7 or 11x6 is not out of the question.
TT46pro my personal favorite teamed with the jett muffler. A bit more rpm and a little less torque than the 46AX. 9x7, 9x8, 10x6
The Tower 46 runs almost the same as the TT46pro - but an example I have seen indicated it was not happy turning the rpm over time.
Rossi is always a good choice.
ST GS-45 is actually a very good engine too - needs the tuned exhaust to really perform. (Could use a slightly larger carb - that is the limiting factor). Figure on a 9x7 on this.
Bob