Trying to Tune my ThermoQuad

I dumped the Eddy 1406 and adaptor and put a fresh ThermoQuad from DemonSizzler on the late '70's manifold on my 318. Those Great BIG holes in the mani were just crying for the Great BIG TQ secondaries. The challenge now is initial setup/tuning of the TQ.

First assembly, without any gasket sealer, and I had a whistle that reminded me of the Bosun's Pipe from when I was in the Navy. I know that's a pretty certain indication of a vacuum leak, so I slathered a thin. but even coat of Permatex on both sides of the gasket, and snugged the nuts down on the studs. Got just a tiny bit of sealant squeezed out all around the carb, so that should indicate a good seal, I think. But still have the whistle. Other symptoms are an intermittant change in idle speed about once per second and adjusting the idle mixture screws doesn't seem to make much difference. I can set the idle speed up to keep the engine running, but it wants about 1100rpm.

I'm guessing that I'm just gonna have to find that whistle before I can expect to get the kind of response I expect from the idle mixture screws and can reset the idle to something more reasonable.

Any tips about just how to find vacuum leaks would be deeply appreciated!

Thanks in advance!