Ted, that Parker chamber repair by Dewey Vicknair was amazing. But I'm not surprised.
I think either solder or the correct adhesive should work if the fit of the sub-gauge tubes to the bore is close. I used a Loc-Tite retaining compound to replace the hardened valve seat in a lawn tractor engine, and even with that sort of heat, it never moved in roughly 15 years. I merely roughened the loose valve seat with a small carbide bit in a die grinder and did the same to the recess in the block. 18" long tubes have many times more contact area. And for that same reason, if Jose chose to go with solder, I'm sure plain old 60-40 tin lead solder would be more than strong enough. Plus there would be less risk of melting the solder joints in the monobloc.
I have no experience with the very low melting point Tin-Bismuth solder alloys, so can't comment.
