Th plan is using the knock sensing capability of the vems unit. But there is small usable info in wiki.
The original 2wd computer has no knock sensor, but the next version the L8 in the 4wd Sierra has it. Unfortunatelly no info about the working mechanism and parameters.
The place of the sonsor is at the bottom end of the block at cyl 4. This is the hottest cylinder, but I think it isn't good place.
The bore of the cylinder is 91 mm so the theoretic knock frequency is 900/(pi*r) = 900/(pi*91/2) = 6.29 kHz