Charles:

The Wizard of Oz has it right, but there are many strap-on mufflers available. Check with Tower and Horizon, or your LHS if you have one.

The Testor's McCoy engines were fast wear-outs, so as DU said, don't even consider a current fuel in it. Probably easiest to mix your own, get a gallon jug and pour a quart of degummed castor oil in it, and fill it up with methanol. Instant 25% oil mix fuel. Going to his recommended 29% is also possible, but 25% really should be enough. And it's easier to measure.

Bill.