Dattoman_1000: I've noticed you use the UC piston and turn it down to remove approx 1.0 to 1.5mm off the top. I've done this myself. It makes the piston very light and it revs nicely but if you mix it with high compression and advance the timing too much it will fatigue and crack the piston over time. However, we've had experience with this setup lasting for 4 years in a double entered car going to most events. The trick is to eliminate knocking and retard the timing. Note: we tried advancing the timing and it reduced the power anyway!!
I'm currently looking at other cast pistons which do not require me to remove any material from them. Have you thought of this option??? I can let you in on what I know if that helps you.
Just thought I'd mention this because costs can runaway sooo easily with racing and if you spend money and it doesn't perform, or worse still, blows up due to another reason (ie valve sticks etc) then it becomes terribly dishartening. After all, the most satisfaction from racing a datsun is beating those late model cars with all their fancy twin cams and efi and possibly even turbos with an old a-series pushrod motor!!
But on the other hand, if one could obtain a set of forgies for approx AU$650 like the ones above.....