Thanks for your replies!
Dave2C, thanks for the tip on the whiting product. I have ordered some from Brownell's and will give it a try.
Deepcreekdale, I certainly appreciate the exercise of caution and care in any antique restoration work. I have not used hide glue in the past, but yesterday ordered a product called "Titebond III Hide Glue" which apparently does not require mixing or heating. I'll try this out on some scrap pieces. In regard to epoxy or acraglas being inappropriate for antique repair, opinions appear to be in flux over time. The late Kit Ravenshear wrote in one of his booklets in about 1993 that he used acraglas in about 60% of his antique gun repairs. R.H McCrory wrote in his book "Lock Stock and Barrel -- Antique Gun Repair" in 1966 that his favorite glue was "Elmer's Epoxy". John Bivins wrote in the publication "Rifle" in 1983 "Because of the nature of handling stresss on the stock, and often imperfect joints because of oil-contaminated wood, epoxy unfortunately is the only really effective adhesive for use in restoring firearms." He goes on to say he uses the word "unfortunately" due to the difficulty in reversing an epoxy repair. He further mentions the use of hide glue, but states that he feels hide glue lacks sufficient strength for major stock repairs.
More recently, Mark Eliott wrote on his website under the topic of restoration that he used T-88 epoxy in the repair of a Gonter flintlock with two complete breaks through the stock, one at the back of the wrist and one passing through the front part of the lock inlet. The latter break is almost identical to the break in my fowler. He stated that he would normally use hide glue but felt that this would not be adequate for these major repairs. Here is the link to his site and the results of his nice repair:
http://www.markelliottva.com/wordpress/2015/04/repair-restoration/Please feel free to chime in, Mark!
As far as sending this to a professional firearms conservator, I don't believe this piece is rare or valuable enough to warrent the expense. The gun is well constructed but does not appear to be an especially high-end piece. (I stated in my first post that it was probably late 18th century but certainly could be early 19th.)
Here are some pictures showing the overall gun and its damage.
Note the iron ramrod, simple V rear sight, missing simple sideplate/washers, brass trigger plate. Proofmarks are mostly obliterated, apparently from a vise. The acorn finial and relatively pointed back of the lock inlet suggested late 18th century to me. Other thoughts welcome! If anyone thinks this piece is rare or valuable enough to warrant professional restoration, please say so. I anticipate doing only minimal repairs, primarily fixing the big break and replacing the sideplate/washers, also finding an appropriate replacement flint lock.
Thanks, Gregg