Both flywheels that I use are 34 mm in diameter. The engine mounts are about 14 mm high in my DM1 Spec (STS .28 engine) and Kyosho (Force .28 engine) cars.
I am using the Ofna Chrome Top starter box with a 12v. gel cell battery.
Hope this info helps you get setup.
"Yellow Jacket" Mugen MTX-6, Picco Torque
TeamNITRO RC Club, Lynwood, Illinois