Cannon and Company and the NP Historical Society both have the same decal set for Combo Door Boxcars in that style in HO Scale, except that they are for the rib side cars, but may be able to be used for the inside post cars like you pictured.
Rick Jesionowski
Rule 1: This is my railroad.
Rule 2: I make the rules.
Rule 3: Illuminating discussion of prototype history, equipment and operating practices is always welcome, but in the event of visitor-perceived anacronisms, detail descrepancies or operating errors, consult RULE 1!
I would put my energy into finding that set I mentioned. It's my impression that it has everything you need.
Ed
Found it for N scale, which doesn't help much. However, I have emailed Microscale for information on that set.
Alternatives: I have a couple of sheets of BN 40' and 50' Boxcar Data/Markings left over from another project that were going to be needed anyway. Those sheets look like I can use them for the dimensional data for the boxcar. Next issue: Are there any sets that I can use for the needed momad size, "Route of the Vista Dome..." text, reporting marks and something that can be improvised for the unique offset NP letters on the left hand side of the car. (The 40' combo cars are the only ones that had the offset lettering.)
My research says you might be happy with Microscale MC-4109. I believe the trick is to find it. I surely can't.
Does anyone know where I might find a correct HO decal set for this scheme?:
http://www.rrpicturearchives.net/showPicture.aspx?id=1911528
The two Microscale sets for NP boxcars that I can find don't cover this particular scheme and I have no idea where else to look. As usual any help the forums can provide would be most welcomed.