I'm trying get my Ac to blow hard like a new car without have to do the vintage air. It blows cold air with the factory ac but doesnt blow out hard. Also, if I'm parked for maybe over 5 to 10 mins idling the blower seems to stop working and then I'll have to keep it off for a little bit and then it'll turn on and then I drive off then its fine.

 

The blower motor can go bad. Unfortunately you need to remove the fender (or at least the inner fender) to access it.

 

There is another condition that could contribute to this. If the charge is not correct (too low) or air flow across the evaporator is restricted, there is a point at which the evaporator coil temp will drop below freezing and if there is enough humidity the coil will freeze and reduce (or stop) air flow. Is this an R12 system? Might want to check that your pressures are correct and that the air coming out of your center vent is between 36 to 40 degrees (windows up low fan speed...with max AC or recirc if your car has it)

 

Ain't gonna happen unless you install a different blower motor that can move a lot more air.

It sounds as if there's a problem with your system, so focus on getting that worked out before attempting to "upgrade" the air flow. I drove my 70 and then later the 71 all through high school, college, and first job and the AC worked well enough to keep me comfortable in Gulf Coast summer heat and humidity. Here in Phoenix the 71 AC does well enough for me to drive during 110+ summer temps.

While it would be "nice" for the blower to move more air like a newer car, it does well enough that I don't consider that effort to be worthwhile.