My 1970 Gibson J38 broke at the headstock.. This is apparently a rather common phenomenon with classic Gibson's... Anway, i have a great deal of woodworking experience, but little with this type of repair.... I went to a trusted luthier, and we talked for awhile about it... He endded up telling me how he would do it, and said that I should go a head and give it a try....
Mind you my heastock broke at roughly 90 degres to the strings... This was diretcly related to age and the stress strings apply to the neck... Anyway
1) remove strings
2) sand and clean the area around the joint
3) drill a clean hole through the break where a wooden dowel can be used to reinforce BOTH parts of the break
4)Clean the dowel by sanding with a VERY light sandpaper... You dont want to make the dowel too small for the hole.. the dowel should have excess wood exposed on both sides of the hole so you can sand it down later
5) apply wood glue to the broken parts... use a Q-tip to spread the glue so that it covers ALL exposed wood at the break
6) Apply glue to the dowel, and insert... The dowel should have to be tapped in by a hammer... The point of the dowel is to prived a secure anchor for the joint and to add strength by reinforcing against the stress point
7) Carefully use a clamp to tighten the joint... Wipe any excess glue off the joint, and allow to dry...
8) After glue is completely dried, I sanded the dowel and that area down and started the painstakingly slow process of refinishing the joint...
I can tell the break was there, but I know what I am looking for... Most people that have played my Gibby arent aware that it has been broken... Those that do know, I told them
A few points....
DONT use Gorilla Glue... that is an expanding glue, and you dont wont that glue pushing AGAINST the joint!
DONT use JB Weld... Wood Glue is made for that purpose... I remember in grade school, my shop teacher to 2 scrap pieces of wood and glued them together.. After the glue was dry, he would slam the wood down againsth the workbench, breaking it... He did this with several different pieces to prove a point... NOT ONCE did the wood break AT the joint... The wood glue joint was stronger than the wood itself...
I am not trying to offend you, but with some of the questions you have asked, I'd advise taking it in to the shop, but do like others have suggested, and talk with them about the repair... There is NO reason they should have to use brass, or any other metal... I think they are just trying to do it quickly... Using metal fasteners will, of course, work... But, with a wooden dowel or two, the joint will be stronger...
Can you post pics, or email them... I might be able to take a look at it and give you some pointers