ABC engines are not lapped with anything. If there was lapping compound in it, someone put it in or someone a the factory screwed up.

Even back in the day of lapped engines using lustrox was a bad Idea. It was poured into the intake while the engine was running. This not only lapped the piston/cylinder, it lapped the crankpin/conrod fit and crankshaft/crankcase fit and that was the front end seal. Bad idea making it bigger/looser rod big end a sloppy fit.

Lapped engines needed a slow long break in. Trying to speed up the process usually ruined them.