only time I ever had a stock engine with 360 heads on a 318 and piston touch valve enough to leave small eyebrows from exhaust valve was when it was over reved and floated the valves.

I never had a bent valve from a jumped chain. now if it was jumped then over reved. I would wager it will bend a valve or knock a hole in the piston.

now I have had warped valves, burnt valves, dropped valves, but never with a jumped chain.

I wont say it cant happen though. I have been lucky to find the other weak spots first.

mid 70s to mid 80s the heads are open chamber 75 and up CC chambers with the pistons 80-100 in the hole. lots of room at TDC.