Putting money into the valiant, suggestions?

Um…yeah, if it runs and drives great, why are we talking about an engine rebuild? Engines that run great do not need rebuilding. Engines that need rebuilding do not run great. First make sure it's in tip-top tune; Tune-up parts and technique suggestions in this thread and the engine will need periodic valve adjustment. Then what you want to focus on is upgrades for safety, driveability, and comfort. If it hasn't already got disc brakes, install them. Invest in good tires and shock absorbers. Make sure the suspension, front and rear, is in top shape. Put in better seat belts. Pick one of the many options for going to electronic ignition; my preference is for the HEI upgrade. Want better performance and driveability? Put in a 2bbl intake manifold and carb and a thoughtfully-configured larger exhaust system. Driving at night? Upgrade the headlight circuit, put in better headlights (see here and here) , and upgrade the rear and side lights. Lots of seat time in the car? Upgrade the radio.