From what I have seen on other sites, your 0-60 in 7.8 is a little optimistic. 13 sec. is slow.
I would suggest you start with the obvious (and cheapest) steps.
Is you accelerator cable properly adjusted for full throttle opening? Air filer and air intake clean? Then:
Spark plugs, distributor cap, rotor spark plug wires (?)
Fuel filter, clean air intake, check timing.
Now that the external engine ar in top shape, do a complete compression check and leak down test.