I'd certainly recommend airing out the garage, the vapor seems like it wants to stick around for some time.

One issue I had in the past with my tri-power set up was if the engine got just a little hot (typical of a b ig block) the gas tended to "perk" out of the bowls. Yes the gas smell, but cold starts were difficult because the carbs were empty.

I would look for a vapor leak in the cannister purge system.  Granted, this is difficult to find.  There is special equipment for helping.  But if you put GENTLE (less than 2 psi) air pressure in the tank, you can use soap bubbles to find a leak.  There are other possibilites.

A "very strong gas smell" would indicate a raw fuel leak, to me. Fuel lines, fuel pump, and fuel tanks can all leak, but not leave a "poodle" on the floor.
My '74 had a leaky tank(rusted out ), with no fuel on the floor, but a serious smell in the garage. It was running onto the spare tire cover, spreading out, and then evaporating. Only took a year to find it!

Check all the lines/hoses for cracks, and don't ferget the vapor separator, on the driver's side, toward the top of the tank.
The vapor/charcoal cannister is on the driver side, front fender area, under the brake master cyl.

Yours is about the same as mine was, a little bit of a pain, but not terrible. Keep in mind that with a big block, you have a lot more mass to warm up. Today's cars are meant to crank and go for efficiency. On older cars it was actually standard procedure to let it warm up before driving. I can remember mom's old 65 Impala even had a light on the dash that told you when it was warmed up.

It does sound like yours is leaking down though if it dies right after the initial crank.

On mine now, it does want to start a lot easier, but still needs to warm up before it behaves. One trick my engine guy told me was to pump the gas a couple of times before even turning the key, wait a couple of seconds, then crank. It did seem to start a little quicker.

You still want to check ken's and adam's recommendations too, fuel vapor in an enclosed space is a bad combination. We like you here!

Keep us posted.

Also, look at the thread "hard start cold" Ken and Sarge make some good suggestions and observations.