1972 Thermoquad (340) Main Jet Well Inspection Question?

Could be normal......if there was fuel in the bowl when you separated the bowl from the base. Fuel could have sloshed out into those cavities. To test: set bowl up on bench so that you can see the jet wells. Carefully poor fuel into the float bowls to just cover the wells; an eye dropper or syringe is a good idea, as too much fuel will run over the edge making it seem like you have a leak...when you haven't; look for fuel weeping from the wells.
Carb looks to be in EXCELLENT cond.
Leaking wells do not affect idle, but can make the main system rich.
To fix leaking wells: use a hacksaw blade or triangular file to remove the old epoxy. Re-fill with fresh fuel resistant epoxy. Do NOT put too much epoxy on or you will break the gasket going over the epoxy 'lump'.