Good point datsunfreak. The better matchbox distributor was on all '79 vehicles so 210s not the earlier B210.
Although not really a performance upgrade the '78 and up vehicles had alternators with built in regulators. Simple enough conversion so you can get rid of the mechanical voltage regulator but much lower down on your list of 'to do' things.
The '76B-210 changed from a 3.90 to a 3.70 differential gear depending on the month. If you have a 3.70 changing to a 3.90 or even better, a 4.11 will allow much faster take offs and improve acceleration in all gears. I can't find a 4.11 listed for the H-150 but you might be able to buy one for racing. Other than maybe poorer mileage it adds no extra strain to the engine and is a few hours work to do, but gives much better performance. I have a 710 with 3.70 and went to a 4.11 and am extremely pleased with it.
Tires, tires, tires. Have come a long way since the B-210 was new. Good grippy tires will out perform a car with more power and poor tires.
Thicker sway bar on the front and maybe add a sway bar to the back to control body roll when cornering.
New shocks. They don't have to be those expensive ones, they just need to be new.