Sounds like you have it all set, I have a set of the 492s their a service head with the angle plugs. On the distributor shims you will have to pick up a shim pack, any hot rod shop should have them. You use a feeler gage set between the cam gear and the distributor housing shaft to figure out what shim you need.
The instructions are in the pack. All you have to do is knock out the split pin, slide off the gear, put on the shim/s and reinstall the gear. LOL
Luv the smell of NITRO in the morning.