starting issue after running for a while.
 

I have a 71T that starts up in the garage fine after sitting for week or two but once i drive it for 20 30 min and turn it off it really has to crank and be fed fuel to restart. I would expect just the opposite would be happening????

Are you certain it's a fuel delivery issue and not an ignition issue?

You have carbs, correct? The only way it could be a fuel issue is if the carb bowls somehow emptied during the 20-30 minute period, which seems unlikely IMO. It starts after sitting in the garage so it can't be fuel draining back into the tank (remote possibility anyway.) Highly unlikely the gas in the bowls has "boiled" away due to extreme heat (but you can listen for it next time you shut down the hot engine) and even if it did vaporize, how would the bowls refill by sitting? If the fuel pump failed, the residual gas in the bowls would fire the engine.

I strongly suspect an ignition problem.

make sure cap, rotor and plugs are in good working order. check timing. make sure you dont have air leaks. check manifold and carb nuts. then mixture, could be too rich. if not, try one range hotter plug.

when it does start, does it run on les than 6 cylinders for a few minutes?