Matt,
The bronze gear is the best, but it should be used with an offset bolt from Xyzer for proper alinement and maximum durability.
As far as a smaller diameter pulley for the 8/1 compared to a 6/1, they both have 23.5" flywheels. So they take the same size pulley.
"We ALSO have new flywheels, both the 6/1 and 12/2 six-spoke versions, and for those who need more HP, we also have the 23.5" Stover wheels (for 850 RPM). A 6/1 at 850 RPM is 8 HP, and a 6/1 at 1,000 RPM with the 20" Stover wheels is 10 HP. Similarly, a 12/2 at 850 is 16 HP, and at 1,000 RPM is 20 HP."
The smaller 20" flywheel is on the 10/1 operating at 1,000 RPM.
My 14/1 has a 23.5" heavy flywheel and its rated at 1,000 RPM.
Diesel Guy