Yes, I think it would do.
The Bisson muffler compares with the 3271 type MVVS muffler. With latter muffler, and the Mejzlik 20x10 prop the engine spins at 6400 rpm (factory data), so your test with 20x8 prop and the compact muffler seems right on.
Entering these data into my trusted spreadsheet, and converting to 3-blade using E-calc's 1.97 prop power factor I expect:
with a 18x8x3 prop the engine would spin about 6800-6900 rpm, and with the 18x10x3 between 6300 and 6400 rpm static.
The 16x11x4 (4-blade, P=2.6) would also spin around 6400 rpm, if you can get such a prop somewhere. I do not know if Mejzlik will make 4-blade props to customer specification, But if you need one it would be worth a try.
All those propellers will be in the right power curve range for the 35cc engine, expect between 16 and 18lbs static thrust. This is enough to fly a 25 to 30lbs warbird in a realistic manner.
At 30 lbs your climb angle will be about 25 degrees at 45 Mph. Level top speed about 85 Mph. Stall speed 35 Mph.
At 25 lbs the climb angle will be about 35 degrees.