Aero-Gloss is still sold. It is "Hot Fuel Proof" and means it can stand up to exhaust residue - trace amounts of fuel but I've used it on airplanes and does okay up to 15%. Look for butyrate, not nitrate dope if your looking for fuel proofness. There is a hot fuel proofer clear that ISNT dope that you can spray over decals and dope to further fuel proof it. Not a very good alternative these days.
A good, cellulose-based varnish has been recommended by Dumas in the past in their finishing instructions. Not a bad way to go if using lower nitro.