My thoughts were to integrate, say 20-25 percent into your favorite mix. If it is compatible.
Just trying to make what you have just a little better.
Even 10 or 15%.
I have used lots of Fullerplast, glasscote, conversion varnish and other modern catalyzed finishes. More than 100 stock finishes of experience.
You don't mix them with other stuff. Well, reducer and catalyst, not not other finishes though.
They are fine on 1970s Weatherbys and bar tops. With those materials it is possible to build a thick finish in one spray session. Fine.... They look really stupid on a muzzleloaders. Just do.
Another consideration is that they are really toxic. Unless you have appropriate safety gear you can cause yourself serious harm.
I understand the good intentions of improving something. That is how I came to how I do stocks today. I do not use any Fullerplast type finishes at all anymore. They are too dangerous, unavailable in my state, and do not look good. They are too thick and can look cheap if not rubbed out right.
Some factory MLs use this stuff and look worse for it.
On a carved stock they would ruin the carving. On modern guns the checkering is done after finishing for this reason.