Babs and I have problems Bliep/Bliep and Bliep... euhm.... let us leave that out....

On the can problem. I have seen what happens with a can of wieners on a gas flame. A painted kitchen with the color and smell of wieners. The can opened a small pinhole and sprayed everything out with the steampressure.

On the gearing problem. Pete, if you can keep the motors cool, you could try for the 12/1 gearing, with a good current limited speedo.
But in the end, the advantages the Bosch 400s have on Graupner speed 900s are the higher torque due the bigger diameter and the higher heat sink capacity due weight.

In Gravity bosch 750s were run on 10 kart wheels, with a 20/1 dual stage reduction
and limited to 36V 75 amps. I doubt anyone would call Gravity slow or not powerfull.