Why not just have a compression test done?
Beat me to it.
Another thing worth investigating is the carburettor float. It was mentioned earlier that it may have been set up for a nosewheel aircraft during overhaul.
It may also have become unseated during storage. I had a similar situation after rebuild of the carb on my J3. Engine ran like a sack of spuds.
Engine shop suggested tapping the float bowl reasonably lightly with a mallet. Fixed the problem.