If the inletting is too large for a Winchester bottom metal and trigger guard set, just have your gunsmith completely fill in the lower portion of the inletting with bedding material and recut everything for the Winchester bottom metal and trigger guard. I've seen gunsmiths like LRI completely fill in all the inletting and recut it from scratch. You don't need to go that far, just do the bottom of the stock where the bottom metal inletting is.
If the Winchester stuff has an outline of bedding material around it, get a paint and gel coat set, and bring out your inner artist! There's guys on this forum who have been able to color match and gel coat McMillan stocks before, I think
@crazynoto has done it and might be able to give some advice. If you're unable to paint/gel coat, then just leave it as is with the outline or rattle can the rifle (leave it completely painted or wear it down in a lot of areas to show the stock's unique pattern).
If the inletting is too small for the Winchester bottom metal and trigger guard, then just open it up like
@pmclaine suggested. Once it's properly cut, bed the Winchester parts and if there's any odd areas that show a lot of bedding compound, get some paint and gel coat to match the surrounding area.
I have no idea if the Remington inletting is larger or small than the Winchester inletting, but it doesn't matter much. There should be absolutely no reason why you can't use a Winchester bottom metal and trigger guard with that stock, it's just going to take a little bit more work. Hell, I might even have some extra M70 shit in a drawer somewhere, let me know if you need the parts and I'll see what I have.