What it looks like you have is a 550 or a 440 pistol port engine out of a JS.
It has a pjs head, pjs exhaust manifold/head pipe, BN44 possibly, "hightorque" starter, and an aftermarket flame arrestor but it is NOT a PJS engine out of one of the PJS skis.
If the engine was running with perfect compression I would price it at about 500$ with everything on it.
Just from a feeling it might be a 550.
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