Anyone know how to do a bitchin burn out, lol !

OP; in your case you want to disable the rear brakes, so you can modulate the rate of forward motion with the brake-pedal operating only the front brakes. Just back off the rear brake adjusters so they cannot apply the rear brakes.
But if you said, mid-70s A-body with a 318, you better not have a sure-grip, cuz if spins them both at all, it won't for very far. But if you peg-leg that 7.25, you better put some fresh, high quality gearoil in it, and overfill it, to get some cooling power in there, else the crosspin will try to seize up the spiders ,usually with disastrous results.
If you do overfill it, then service your vent and install a 2 to 3 ft hose on it, and anchor the free end up on the shock crossmember. Leave some slack for suspension travel, but not enough to allow puddling in the hose. This is to allow the hot oily vapors out, and to allow the oil to run back into the tube, instead of onto the road.