The last aluminum Scheifer wheel I ran, had a riveted in metal plate. A little more difficult to replace when it wears out. But m feeling is that a 15 pound flywheel in a car that heavy with the gears you are planning on running is going to be a real bad fit. The lighter the flywheel, the more effort it takes to create the inertia to move the car from a stop, meaning more into the gas, higher rpm, higher slip, more wear. I'm not real keen on your 18 pound flywheel with 2.76 gears, either, but the 15 I would not attempt at all.