If it is truly HC pistons, pre-ignition is the risk with low octane fuel and may not be detected until you have done irreparable damage to the engine. Recommend you find out what is in there before you run it. Ask the previous owner what gas he used, then get the documentation for the piston kit.

 

Dude, he already stated he can't contact the previous owner. Besides, being 1.5yrs later, Im sure he's either been running 91, running 87 and doesn't have higher compression, or blew it sky high already.

 

Sorry i missed the post date