On my stand I have a place where I jamb a 2x4 and lever it against the flywheel to create a load. A bucket of water for dipping is alongside. On your band brake you will want to direct a good stream from a garden hose to keep things cool.
The 2X4 sounds like the better way to go. I could get the truck transmission but it's not what I want when the time comes for this to be mobile. When you lever up against the flywheel, I assume you're going to the face of it right where the friction plate rides. I'm guessing you've never had any trouble with the trust bearing. I can do that a heck of a lot cheaper and no lump of unsynchronized iron laying around when I'm done.