A little different method...I did this just last week.
Rub with Montreal steak spice night before, wrap tight.
Day of, set on counter, let it come to room temp (maybe 2 hours).
Preheat oven to 500F.
Place roast on rack in pan and into oven for 1 hour (this will sear the meat, leaving the inside raw).
Remove, let cool.
Fire up the grill. cut away the rib bones, slice meat into serving sizes (as thick or thin as you want). Grill bones and slices to desired doneness on grill (preferably hardwood charcoal).
Do you by any chance have a propane blowtorch? I can't say enough about how well the Thomas Keller Ad Hoc at Home recipe worked for us. Basically, you season the roast, then scorch the fat on the outside, then put it in a low oven (I think we ended up at 300) until it gets to about 10 degrees below ideal temp. Cover with foil, and rest. Good crust, tender meat. Make sure you have a thermometer, as you will need it.
Otherwise, I would agree with high heat for 15, then turning it down to finish.
Assuming this is bone in, I would dry brine it in the fridge with a healthy sprinkling of kosher salt on it, and leave it uncovered in my fridge until about an hour before I want to roast it.
This way, no need to use high heat, you can roast slow, at this point for a few hours, or roast at a higher heat for less time, but it will take less time to cook and brown, thanks to drying it out in your fridge first. I would use any reputable recipe's guidelines (heat & how long) to cook it, it's not that hard, then adjust by about ten to fifteen minutes (take it out and take temp), and remove it before it gets to your desired temp. Grilling is also a nice way to go.