Dennis:
Nice selection. I don't quite understand why the original had to add 16 oz. of lead to the nose however. Maybe it was because he chose to plank the entire tail section with sheathing, then add fairing strips outside of that. When I did mine, it was 60" and I did not have to add any weight to the nose. I did have a Saito 90 twin and an on board D-cell for glow assist, but no weight was needed. My method of building was with an 1/8" crutch, formers, and fairing strips. I had no planking except in the forward portion of the fuselage. I will bet that you can build much lighter than the expressed 9.5 pounds. Also, I would not be concerned about the strength of the Saito .52 Surpass. I'll bet it would be ideal for your Mulligan.
Jim Fruit