I've been asking around different places and couldn't get any good answers, but I just discovered that the Gotoh locking nuts uses metric radius, so I checked with a ruler and this is the answers!
The wider nut (GHL) has 400mm radius = almost 16"
The narrow nut (FGR) has a 360mm radius = about 14"
So that is actually interested for a good reason;
OFR offers a very limited range of locking nuts, most being 10" and ONE 12" (R3), and then a couple of 15" as well. Now that most guitars uses a 10-16" compound radius, this is not a big deal, but if somebody wanna have a custom neck or something, Gotohs can be a good alternative
And Gotoh locking nuts (with rear bolt) ARE interchangable with OFR locking nuts, at least R4, because I have swapped a R4 nut for a Gotoh once. I did notice that the outer strings was a bit higher than the middle, but I couldn't see why because I really thought it had a 10" radius when buying, but supposed it was 12" after installing... Now I know it's fucking 16". Hahaha!!!
But this can be a good alternative for a straight 16" Musikraft setneck strat for a future build, actually
Gotoh make a range of lock nuts to suit the most common sizes and styles. Basically between 41 and 44mm width and radius of 10, 12, 14 and 16 inches to cover most all common radius. They measure theirs in metric but realistically the margin of difference between the metric and imperial measurements is negligible.
If you were going to have a custom neck made, chances are you'd just have it made to a common radius as I'm pretty sure very few of us would be able to tell the difference between a 12 inch radius and a 12.3 inch radius.