PG is a great drag racing transmission within "limits". It's tough and the internals are relatively light for their strength. TONS of aftermarket parts available to make them tough enough for over 1,000 HP.
"Rule of thumb" In a car under 3,000 lbs., a 'glide will have a slight advantage over the TH350 or 400. Converter and gearing are critical. For cars over 3,000 lbs., and less than 600 HP, TH350 gets the "nod". When properly built, tough enough. The "deep" 1st gear makes for some good 60' times. For heavier cars with more than 600 HP or more than 500 lbs. of torque, TH400 is (IMO) the best choice.
For a street car with "taller" gears (in the mid "3s") and less than 500 lbs. of torque, TH350 is called for. IMO, PG is not a good street transmission when more efficient units are available. If you want the "lower" gears like a drag car, TH200-4R ("built") would be my choice, with TH700-R4 another consideration (keep the power lower with the latter). The OD makes it "drivable".
Jim