The grain fill was made by LMI and I believe it's the mahogany ... or maybe just called dark brown ... not sure, but it resembles melted chocolate when it's in the plastic container.
I did 3 grain fills with the dark brown waiting 4 or so hours or maybe a day between 2 and 3, for it to dry and then sanding lightly after with 320 or 400 to remove the excess grain fill left on the surface. Wipe with lighter fluid to remove sanding dust. Waited a day after last grain fill, sanding and wipe down, before final sandings, wipe downs and master-gel.
Final sanding was then a pass with 600 and then 800 wiping down with lighter fluid after each then directly to the first coat of master-gel.
4 coats of Behlin's Master-Bel total, wait 1 day,
lightly buffing with a white scotchbrite and wiping down with lighter fluid then next coat,
wait 1 day, etc.
and only handling it with cotton gloves.
I let it sit for a few days after the 4th coat of Master-Gel buffed with scotchbright, wiped with lighter fluid, and then wiped it down with Formbey's Lemon Oil.
I'm not sure if the lemon oil mattered but I have it so I knew it couldn't hurt.
I used lighter fluid to clean off sanding dust after grain fills and after buffing with the white scotchbrite.
That's it.
The Behlin's Master-Gel is very forgiving and easy to use. I did a few test runs on un filled honduras mohogany before I did the korina and those little 4" x 4" blocks came out looking great. All I did with them is sanded smooth up to 600 grit, wiped off with lighter fluid, and then hit them with a quick coat of Master-Gel waited a day before buffing with white scotchbrite, wipe down with lighter fluid, second coat, up to 4 coats total.
My waiting times might be incorrect because I may have waited longer on a few, because of being busy with other things, so I'm just telling of the shortest wait times meaning don't go any shorter.
The brass trem block:
Was reported to have more solid midrange tone and more sustain than the steel block but since I never used the original steel block I can't testify to the truth of that comparison. It certainly feels like a real beefy chunk of metal compared to the light little steel stock block.
It does sound nice and solid, and also sustains comparably well to my hard tail mahogany strat.