What Carb for Poly Stroker
The difficulty with the Thermoquad aside from age is that like the Quadrajet, those big secondary throttle plates will not clear the factory manifold. True that a carb adapter could be purchased if there is enough underhood height.
IMHO for mainly street use, go with the AVS2 650. Nothing wrong with the Holley style carbs. My 289 2V did require a bowl gasket every spring or at minimum tighten bowl screws as the gasket dried and shrank over the winter. For me the Edelbrock performer 600 on an Airgap manifold cured that issue. I believe there are better gaskets available now for the Holley float bowls.