My thoughts on 300 horse with a 318. Uncle Tony tried bolt ons but never dynoed it and didn't show a timeslip when he raced Casper.
A Uncle Tony spin off is the MI 318 and they are doing more than just bolt ons for the HP its for a reason.
lunar outlaws 318 had uncle Tonys hands on it was a complete fail and if I recall correctly dynoed at 235 HP at Nicks garage which is what a stock pre 70s 318 is rated. That Engine had Uncle Tonys "port work" done to it.