Walt,
The 944NA and Turbo are the same, it's just that the Turbo has a lot more extra stuff shoehorned into the engine bay.
Behold the area of concern (images copyright Pelican Parts)
You can see that the cap is held on by two spring-loaded clips, which have a philips head feature at one end and an L-shaped protrusion (the "Protrusion") at the other.
To fasten the cap you place it in position and then rotate the clip until it engages a slot in the cam tower. In order to position the clips so the Protrusion grabs the slot, you must push DOWN on the clip to overcome the spring pressure, then rotate the clip with the pressure applied, fit the Protrusion in the slot then release pressure.
The upper one is easy. The lower one requires use of a screwdriver bent 90 degrees, and the Official Factory Swear (Himmel. . .Herrgott etc. etc.) The reason is that there's no clearance, the headlight linkage gets in the way.
See,
infra.
I hope this discourages you from ever going near one, I think you're a terrific guy from the couple times I met you at Parade, and would hate to have you suffer the same VEXATIONS I did.
(I realize this is all related to your scrutineering, so it MUST be done. Perhaps welding some wing nuts to the heads of the clips, so that you can manipulate them AND index them to the slots, would be the solution for a fixture that would allow you to encode the cam rotation when you measure the lift. Getting the cap back on would be the responsibility of the hapless racer
)