Multiple issues here:
1) The heat crossovers cast into the heads and through the intake help solve drivability issues while the car is in "warm-up" mode. Where you live (up North), I'd think you would be better off letting the heat warm the intake floor for improved drivability.
2) Fuel dripping into the intake while off: seems you might want to replace the needle and seats. Today's fuels eat the soft rubber (ah, whatever its made of) so fuel will continue to leak through even after the car is turned off while the fuel line is de-pressurizing.
3) fuel dripping out of the butterfly shafts: Probably well worn seals. I think in the old days Holley used leather, but either way likely seals.
4) One more possibility about leaking fuel: 87 Octane fuel here in the States containes 10% ethanol. Eventually, the ethanol eats through the bottom of the fuel bowl(s) in a microscopic way. You can tell where the leak is, but might not be able to see the hole.
Rod T - Former Certified General Master Mechanic (ASE) retired.