Hi

Per factory: A 1972, 117.98(1,2,4) using cams 52/53 measured on cylinders 1 & 6.

With a new chain

Left Cam
Intake valve opens@ 4 degrees TDC then closes @ 14 degrees BDC
Exhaust valve opens@ 30 degrees BDC then closes@ 16 degrees TDC

Right Cam
Intake valve opens@ 2 degrees TDC then closes@ 12 degrees BDC
Exhaust valve opens@32 degrees BDC then closes@ 18 degrees TDC

I believe it is Before TDC & Before BDC

If anybody has more to offer feel free to chime in!