D500's suggestion modified with your own...JB Weld, rather than straight epoxy...is how I'd tackle this job....once Brasseur's has been given the try. It can be done...quite well, in fact. Just take your time, lay out your tools, try-fit your parts, pre-plan clamping or supporting techniques/tools.
Alternatively, these are the sorts of things that make York meets interesting....the search for the elusive!
One 'good' thing about this sort of boo-boo....it's more cosmetic than functional. IOW, the regular operation of the engine isn't dependent upon this fix. And, it won't be subject to regular stress.....unless opening and shutting boiler front doors is a fixation/habit of the unsupervised grandkids!!!
We're looking forward to being inspired by your repairs!!
KD