Thanks guys for the input. I'm glad to see some of you like to break the rules.
Btw, duxthe1, I'm not actually diagnosing any problems. I run my M119 on 91. My question was hypothetical. The idea just occurred to me, so I had to share.
An exhaust cam that's 23* behind the crank angle, or cam angle? Either way, that's a lot. I didn't think the tensioner could take up that much slack. I measured mine recently, and it was only about 3.5* crank angle.
I hear you on the warm-up map issue on the 70* thermostat. That's doesn't sound like a good idea.
I think the best way might be to check the variable cam retard angles during controlled conditions using a real-time scanner while being on:
(a) 91 octane with specified heat range plugs
(b) 87 octane with specified heat range plugs
(c) 87 octane with various lower heat range plugs.
Another idea might be to try the above with option (d) water injection contra-proportionate to fuel injection (i.e., max water at lowest intake vacuum).
If you all have more comments, ideas, or experience, please do post here. If promising, I might take this up as a future project.
Cheers