[KTL]

You're correct that the fit of the sprocket over the cam snout needs to be loose enough that the two can rotate independently. If they are too tight because of the black stuff applied to the cam, you need to clean that off. We need them to be free or else you can't re-index the vernier assembly to allow the pin to be placed in a different sprocket hole.

You don't need to get another bolt and a nut. Just tightly bottom the original bolt in the snout of the cam and use that as your way of rotating the cam. Then cam can be turned with the bolt head. You just have to strategically install the bolt in the cam at the right time, w/out the big fat washer in place. Basically you use the specialty counterholding tool to hold the cam (with the indexing hub + woodruff key, chain sprocket and retention pin in place) and then snug the bolt all the way into the cam snout to create thread interference like double-nutting.

Once you've done that, pull the pin and use the tools to rotate the cam as desired to change the TDC overlap lift amount. Then hold the cam with the nut, put the pin in whatever hole will take it, put the sprocket holding tool back in the sprocket, remove the bolt so you can install the big washer, put the bolt back in torqued to spec, rotate engine 360 degrees and check your lift spec. Repeat as necessary.