[sidehacker]

I have built several 68CI engines using 61 flywheels and 74 barrels at 3.5 inch bore. They rev nicely and pull hard as well as being very smooth running. I like them well enough that I plan to build one as my next knuckle project, a '40s TT replica.
H-D themselves used such an engine in the '40s for some of their military projects.
Robbie

Did you have to use a 61 cam?