I tend to agree with Glasscutter on this. In 70's and 80's stock form, the 455 Olds is a far better powerplant for a jet boat than the Chebbie or the Ford. More torque, none of them ran even AT 5k rpm, and pretty much bullet proof in that application. (Jet drives, from my understanding, were built initially around the old 215 Olds engine to begin with).
Nowadays, the advent of the "crate" motor and boat shops such as Harmin and Harden, have pushed those platforms well above what was ever expected from these engines and boats. And Jet shops, Tommy included, have built jets to take advantage of that. Not a bad thing, beleive me! It's the last bastion for us old school hot rodders, since street hot rodding is limited due to emiisions, etc, and the bar is set at these $100k+ machines you see at Barrett-Jackson.
I am a huge fan of the Olds and Poncho powered boats, and mods necessary that we used to do on street cars I, and others, have posted elsewhere, but Glasscutters on the right track! Glenn's also right, it's not an oil problem, it's over oiled for extreme rpm useage is all.
In stock form though, given the same boat, jet, etc, and given a choice between the three engines built to 70's stock spec, I would take the Olds any day. It's only because we, in our nature, can't leave chit alone where the Olds is more difficult to make competitive on the extreme side. (Mopars can easily do all of this as well, as Tom has proven recently).
Food for thought on these BOP engines. Buick built their 455 as a straight, almost complete, copy of the Olds and Pontiac 455's. When they decided to enter the Muscle Car arena, too late, in 71-73 they built 2 Buick GS upgrades. The Stage I and the Stage II. Very rare today, but both of those would probably eat the Hemi cars of the day. Ran up against a Stage I on the Docks in Erie PA back in my day, mid 80's, that thing beat me two out of two, BADLY, and I was running a 73 Nova with a tunnel rammed 427, M21 4 speed and 4 linked 9" Ford rear! That thing looked like a completely stock grocery getter, save the Stage I emblems on the fenders. I can't imagine what a Stage II is like!
What would it be like to build one of THOSE motors on a jet boat?
Ray