70aarcuda, the strength of the 318's bottom end is what is in question. I stated that I know a guy that spun a stock bottom end 318 7200 rpm's for 4 yrs. This was to state the 318 bottom end is tougher than what most people give them credit. Yes, they made him pull the head on a record setting pass during an eliminator class meet and he had nicks in the pistons from valves floating and disqualified him for "too much lift" on the valve.
P.S. His name is Jim Peterson, racing at Cordova Dragway, builds racing transmissions for all makes, and has made more passes in his truck than probably anyone in any car. He is a die hard mopar racer that goes back about as far as "Arnie the Farmer", which started his career at Cordova. Jim finally spun a main bearing in his 318 after 4 yrs of 7200 rpm, every weekend. But, anyone can believe what they want.