Post a pic and you might get suggestions for a home fix. Have CA'd small cracks for years as well as using very small brad/finishing nails on a few with only top of the small head of the nail showing.
I'd use wood glue. Put on a liberal amount then shoot it into the crack with some canned air. Clamp it and it should be good. I just got a '63 Dan with a leak. I lubed it with Mac-1 Secret Sauce, put 4 pumps in it and left it overnight. I did that twice and the leak was gone.
The water soluble yellow carpenter's wood glue or Titebond and clamping, as 39M suggested, should work well on that crack/canyon! Be aware of where it will drip and mask stuff off.
"...don't know if Timmy can or will solder another valve in it..."He resoldered the valve back into the basket case first variant Benjamin 392 he Steroided for me.