Richard, that's the SP black widow scheme, I think you can get decals for the nose stripes.
At some point it must have been repainted back from lark grey and it doesn't look like a GRIP or E variant so went off SP books early.
The RC model will need different roof fans to make this one, there are three basic fan set ups on GP9's, from front to rear (middle is always the dynamic one).
Phase I (36"-36")--36"--(36"-36")
Phase II (36"-36")--48"--(36"-36")
Phase III (48")--48"--(48")
I've an inkling there may be a Phase IIa (48")--48"--(36"-36") but I'd need to check as it may be Railroad specific and a local shop application.
The RC model is a Phase II, the engine above is a Phase III, but....has Phase II door grills. I've an inkling there may be a Phase IIa (48")--48"--(36"-36")
If you have a particular engine in mind I've probably got photos of it off the web over the years...I have collected rather a lot of GP9's...
You can just about do a chopped nose SP unit with the RC body shell, there was a small factory batch of Phase II engines where doors and grills matched but had a chopped nose, they also have a landscape windscreen and Phase III fan arrangement, those would be the only changes needed. Other chopped nose engines had different door grill arrangements and the chopped nose is more synonymous with the later GP20 program.
Fuel tanks, SP opted for the full width tank, other Railroads opted for smaller ones sometimes, UP had some smaller tanks, as did DRGW.
If you're seriously into SP GP9's then I recommend the following book for references.
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Southern Pacific Historic Diesels Volume 7: EMD GP9s by Joseph A. Strapac: New softcover (2000) | Arizona Hobbies LLC
Beware, some folks will try and sell it for £50-100 and play on the Strathpac name and out of print hard to get trumpet, load of bollox, shop around and you can get an excellent second hand for £20-30, this one listed above says new at $30 so that's remarkably good value.
One of the more rarer ones is Volume 2 the hydraulics, they go for silly prices, took me years to find a good copy at a decent price.
Diesel Era also did a run on GP9's in general, covered about 20+ magazines over the years, SP I think covered 3-4 magazines if you include SSW variants, UP covered 5-6 magazines, I'd have to dig them all out to be sure and which editions you'd need.
JB - There'll be one for DRGW as well, though I haven't moved that to the special interest shelf. so it'd take some time to dig the details out.