[Lou Hayes Hayes Guitar]

for anyone’s future reference: It had a hidden wood screw from the neckblock into the dovetail and some sort of epoxy was used. Not an easy neck removal

[Lou Hayes Hayes Guitar]

And then use 3 machine bolts, nuts and washers ; Gibson style

[Lou Hayes Hayes Guitar]

I agree with Ian’s answer, however, I have to ask did the customer ask you to change the string spacing? That is not clear in your question