Atlas would have to scrap their current RS3 molds and start over to produce a scale RS3. Too bad they didn't get the Weaver RS3 molds.
While I don't have an Atlas RS3 I do have both the MTH and the Weaver versions...IMO not a lot of difference between them as far as shape/size of the shell:
Here's some measurements:
MTH - 1.68"
Weaver - 1.58"
difference - .10", less than 6 scale inches
Height from walkway to top of hull:
MTH - 1-7/8"
Weaver - 1-13/16"
difference - .0625", 3 scale inches
Length of body from end to end of shell:
MTH - 11-7/8"
Weaver - 12"
difference - .125", 6 scale inches
Almost enough so you can't see it standing 2 feet away.
The nose contours everybody says Weaver got right and everybody else got wrong, I don't see a dimes worth of difference between the Weaver and MTH contours.
Here's a drawing out of Mainline Modeler, but it doesn't have the dimensions I posted to compare to the real deal:
and something I found that shows the difference between the 3 phases:
Unless you're a proto 48 modeler, I feel just about any (I can only go on the ones I have) RS3 would suffice, although 6" difference is pushing even my acceptance level
I don't know if a true scale RS3 would have the room for any of the can motors being currently used. The Weaver, being the smaller of the 2, has little room left with the Pittman motor inside.