I see you have only experience with a Savage (normal clutch) and a .28 engine.
Do not get fooled about an high rpm. A savage will engage at maybe 10.000~12.000 rpm while with a centax type clutch the NT1 has an engage point of 20.000~22.000rpm. Also the top rpm of a non modified .28 will be somewhere about 36.000~38.000 while your RB can reach with easy 44.000rpm.
But messuring the gap is easy.
- Remove the bearing closest to the spring nut
- mount the hole clutch
- push the clutchbell to the shoe and be sure it is on the shoe
- messure the distance from the top screw to the 1st gear with a caliper, if you have a digital one set the messured distance to zero
- pull off the clutchbell and push it to the thrust bearing and messure it again.
- the difference is the gap, directly shown with the digital caliper
There are tools on the market you can stick between the end tip to determ the space, sadly enough I have seen many which are not acurate or are even complete rubbish. If you have one or get one it is wise to check all steps with a caliper if they are right.
And maybe this will give an extra help: