I'd believe some guys'd try anything. Here's a story about kart racing about which I know nothing.
Read a mag article a few years ago in which "they claimed.................."
They had a kart class "designed" to be cheap to race. They specified a certain model BS engine that you HAD to run, and you could not do anything to it.
BUT "in the rules" there was a clause that said if you blew a rod, damaged the block, it was OK to weld up the damage and repair the block
SO....................
guys were cutting out the cam bearing sections of the block, and welding/ brazing them back in to reposition them TO CHANGE CAM TIMING!!!!!!!!!!!!!!!!
So instantly a "cheap" class is now at the mercy of the "play to the rules" crowd.
======================
I also remember a 70s? article about a guy who won the nationals Pure Stock with I think a Buick GS. He worked for a dealer, who had money, so even though you could not blueprint the engine, they did stuff like bought a whole basket of pistons and picked out the closest 8