Thermoquad Rich Idle

The Thermoquad on my bone stock 1973 440 (motorhome) is about to get tossed in favor of a Holley, but I thought I'd come here first. Basically, I pulled it off two weeks ago because it had a jet well leaking. Got that fixed with Seal All and rebuilt the carb, but can't get rid of a rich idle condition. Fuel looks to be dribbling out of the boosters and one shot of the accelerator pump seems to dump in a 1/4 gallon of fuel. At idle, the primary throttle blades are drenched in fuel.

- Floats were the first check. I tried anywhere from 29/32" to 1-1/4" (with gasket on to the top of the float when the air horn is upside down). No change.
- Tried two different sets of brass floats to make sure nothing was funky with one set or the other. No change.
- Needles are new and clean.
- Metering rod tree is working as it should. Metering rods are not bent.
- Very little throttle shaft play.
- All vacuum ports are plugged for tuning purposes (although I also tried it with them hooked up to the corresponding components).
- Sprayed ether everywhere to check for vacuum leaks. No signs of one.
- I've tried both kinds of primary well seals; the x-rings and the o-rings. Thoroughly unimpressed with the fit of both. The ID of them seems to almost be too big to functionally seal.
- Carb to manifold gasket is the thick one, as the engine came with.
- Had a spare, non-leaking phenolic bowl so I swapped it in to make sure warpage wasn't an issue. No change.
- The rebuild kit was a Hygrade 657C.

A 600 cfm Holley 1850-3 is on deck. Between the janky jet well setup and the hokey primary well seal on the Thermoquad, I don't trust this thing at all.