first of all, why would you want a freewheel on the drive side?
second of all, there are a FEW manufacturers who do make left hand drive rear bike wheels (bmx, 20" rims). sometimes freestyle riders like to have the crank chain on the left side rather than the right.
even if you tried a flip-flop hub, the left side sprocket would be threaded on the wrong way and it would come loose when any torque is applied to it. Most of this stuff that i'm talking about is for 20" wheels.
Even if you did put a freewheel on the left, you would have ot get a pretty big sprocket for the engine because if you run a standard size single speed rear bicycle sprocket, it would be too small. the biggest sprocket they make is like 20 teeth.
so you're gear ario would be really high (10 tooth in the front, 20 tooth in the rear.0
you would have very little power from take off, but your bike would probably get up to 60 mph after a few miles.
explaine better on why you would want a freewheel on the left.
if it's because you are worried about the rear wheel locking up, a freewheel wouldn;t help.
just make sure that your drive chain is aligned right, that your wheel bearings are well greased and adjusted right and you'll be fine.
a rear wheel can lock up if your chain comes off and either ends up in the spokes, or bunches up under the sprocket cover on the engine.