looks like it turned out for you.
I hate to say it but i'm always skeptical when people go swapping a bunch of parts on their 1911s like it's a Glock. As you say, fitting was required. Working in a gun store for a while I just saw too many 1911s go out the door only to show back up as non-functioning paperweights when someone got ahold of a Brownells catalog and started ordering parts.
Please keep us posted on range time, not only for a function test, but I am also curious what you think about the RMR on a 1911. I've had RMRs on Glocks and like it a bit, but it sounds interesting on a 1911.
As for the resale value of your Remington R1 slide: not sure on that. I think they're fairly specific to Remington frames if you're going to retain the use of the firing pin block. Maybe a couple hundred bucks to someone looking for something to play with? With the vertical serrations and odd dovetail sights i'm not sure what role it would fit in for someone.