Ok...back on the PC now.
The method I was talking is for in the oven but I figure my grill can do basically the same thing. It is supposed to compensate for getting the inner meat, near the bone, to cook without drying out the outer meat. It comes from Cook's Illustrated but is from Big Daddy's Kitchen (some site I found).
So you start out at 425, cook for 35 mins (for 5-6 lb roast) but then remove it and let rest for another 35 mins (doesn't say whether to tent it or not?). Reduce heat to 325. During this time, internal temp will continue to rise up to 30 degrees as residual heat from bone cooks adjacent meat, allowing it to cook from inside out.
Then return roast to cook for another hour to hour and 15 mins or until IT reaches 145.
Then (of course) LET REST for 20 mins, at which point IT should be about 155.
Point to explaining all this is -- that fat cap won't have much time to crisp up so that's why I'm wondering if I should shave some off the thicker part? Although maybe leaving it really thick would help 'insulate' the outer meat?
Please don't tell me I'm overthinking this I KNOW I am...lol. But really, I'm just trying to learn the science around cooking a leaner cut of meat. I have really only done ribs and butts and whole chickens so far, and that's low and slow.
Thanx again all !!