There is a definite parting line between the two halves but I would assume that a brazed joint would have a clearly visible yellowish layer between the right and left barrels.Nothing like that exists and the two halves appear to have a very close fit and no readily apparent method of fastening the sides together is evident.
I am sure that the lumps are securely joined and not concerned of there integrity.When the top rib is milled away to make room for the new quarter rib more can be seen. Might be able to TIG a nice neat bead to reinforce the top side. Thank You!