Get your car tuned properly, lean mixture and full throttle = detonation = vented pistons = $$$

Change your brake fluid. Brake fluid doesn't last for ever, I know you have plenty, and you can see it in the cylinder, but OEM Brake fluid in a Datsun is WAY passed it's use by!
I'll get a little technical, Brake fluid is Aquascopic, what this means is it Absorbs water. Brake fluid boils at 300+ deg, water 100, that's why your pedal goes a bit spongy after a couple of applications of the brakes coming off the Port Hills, the water is turning into gas and then being compressed as you press the pedal, frantically. Don't let $10 for fresh brake fluid ruin your night at the track, or your paint job, when you run out of STOP.