OK, I've decided to do this version (& keep the Airfix nose for my MaK kits as Dr YoKai suggested) - possibly with the fuel spheres instead of the cabin tho ...
After some research, it would seem that the Airfix Eagle is around 1/110th scale so I settled on the Revell 1/100th Lunar Lander kit as the cheapest way to go for a replacement cockpit pod. I think that if anyone else is going to copy this conversion they should go with the slightly larger Revell 1/96th Lander - even this very-small size difference should look better.
The Revell 1/100 kit is adequate for the scale with some detail that is equal to the larger Airfix kit, a small decal sheet with USofA lettering & a flag but no window glass, just holes where they are, so use Krystal Kleer or blank them off & paint gloss black. It only has a few blemishes from worn molds.
I'm trying to soak the decals off the old Eagle's gloss paint job but they don't seem to be shifting - I may have to try use the caustic-soda bath & hope they survive ok which several other kit decals have when I've resorted to this method of paint removal. A weeks work & I should have the bits read to start putting it all back together again.