which flywheel to fit nitro buggy engine .21 with sg style shaft

[Andre girouard]

Hello all. This is probably an old topic for some but im looking at powering a small deep vee with a .21 dynamite nitro buggy engine that has a sg style shaft, typically found on these engines. Looking for a marine type flywheel that will fit out of the box, the threaded part of the shaft has 1/4-28 threads. I know nova rossi sells a kit to use car engines in cars but at $90, too costly. There are thin flywheels available on ebay like the gp18, which are made for .18 engines. Looking at older internet threads i see that the os Flywheel for .15-.18 engines is used but that has been discontinued. Octgura has flywheels but they would require machining. Any info is appreciated.