I see the manifold is off to the welder, but I have a trick to those who are following your project. I (like a dumb butt) backed my 54 fordson major tractor out of the shed during a large snow event and promptly snapped the cast manifold / exhaust pipe off.(RODE UP THE SNOW DUH)
I took it to work (tech school) and one of the welding instructors quickly laughed at me and said "Nope".
Ever determined I talked to another INSTRUCTOR who promptly directed me back to the first. sensing my determination he told me to go Heat it up. (900) and weld a 6011 rod on it. if it stuck come and find him.
Apparently not all cast is the same. if a 6011 rod sticks to it warm, then some magic rod that he keeps in his office will weld it just fine. ($9.75 per rod) I assume of nickel content.
Short story long. with some careful sticth welding I saved my manifold/exhaust pipe. and he told me to not go crazy with the grinder.
I also used the Brazing technique to save a transfer case on a IH scout. I jumped the truck and found the front drive shaft to be too long. It snapped that case apart like nothing. I worked on that jig saw puzzle for days, but brazing rods are holding to this day. (yes I put in bump stops).
Keep up the fight.
mike