Don't know about the GlueBoost, John, but the last guitar I built out of coco I pore filled with Zpoxy after giving it a good alcohol wipe. There was still quite a bit of red that came up into the epoxy. I was also paranoid about red migrating from the coco to the maple purfling strips so I did some of the binding after the coco was epoxied.
A long time ago I did a little test on some koa with Zpoxy, thin CA and standard paste filler - I felt that the Zpoxy did a better job of popping the figure. And I personally react so badly to any CA that I would be terrified using it as pore filler - I have to wear a respirator any time I work with the stuff.
Also, sorry, I can't comment on shellac. I use it sometimes as a base coat or to seal wood but not as a finish in itself.