Picco sold a rally engine when they had the Evo2, I believe the main difference was an off-road coolinghead, but there might have been some alterations to the timings as well. But Tecnopower, RB, Rossi, Novarossi, OPS (sure i have missed some) have them.
The biggest disadvantage is the lack of torque down low, but extra care when assembling the drivetrain will cure much of that (=reduce both mass and friction).
I´m not saying my route has been easy to take, pipe is critical, no commercial race fuel have worked well and the carb have needed work on throttle, needle and venturi to work at all (just to name some of all the things done).
Tune by smoke or temp won´t work well (95-100c and it´s to lean, 85-90c with almost no smoke at peak rpm and it runs perfect).
But on tarmac it will hang with 2-shifted GT-cars...

Sorry if it became slightly of topic, this was about a racetrack, not my somewhat unusual mod/route.

Lille-bror:
Give me a shout if you´re in need of a "store-bror" and I will take you up on that cold beer!