Jack - the W-1, like most carburetors, will leak around the throttle shaft from the use of modern fuel when a hot engine is turned off:

Leak by throttle shaft

Other than that, it should not leak! Well, maybe, if someone installed either an electric fuel pump, on one of the new chinese mechanical knockoffs!

If you reused the old idle jet without expanding, the idle will be rough.

If you did not blow out the idle passages, the idle may be rough.

The metering rod does nothing at idle.

Popping back coming off idle could be a host of issues, I would start with a compression test!

A professionally rebuilt W-1 (483s, 574s, or 684s) should run well on a 235 up to maybe 200 RPM of where it would run with the 235 carburetor. However, it should run RICH, not lean.

Don't guess, do some testing: compression, ignition, then carburetor.

Jon

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
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The Carburetor Shop