Took some photos of the 1985-issue "75 HP" Revmaster heads for posterity. Compare these to the cooling passages and fins shown on Mark Langford's website: http://www.n56ml.com/n891jf/vw/
Intake valve diameter: 40mm
Exhaust valve diameter: 32mm
The off-axis spark plugs are the Revmaster added secondaries. You can see the left half of the "EMPI" logo on the floor of the rocker box. There is a "75-2" stamped on the exhaust flange at photo right.