I gather is a space on the stayblot and thick of the steel which could be fix by replaced the boiler with a new one.
The ERA 2010 boil can be made.
I think the amount money spend allread is so hi. The $700.000 should be the right amount with the old boil, Add $300.000 for to it design and drawing of a new boiler.
The boiler shop take a old boiler as a model an the $700.000 portion for old boiler and the $300.000 will go the new boiler.

The Pacific Southwest Railway Museum spent well under $700.000 the take a S.P. #2353 Baldwin that receive in 1917 a ALCO Boil 4-6-0.
We got the Locomotive from a park an fix the 5 axle,cylinders,an complete air include the rev sys.

(When we had the Shay #3 I was the bucker for hold the staybolt will me inside the firebox an hammer on the outside.) Noise-----
We sent the Shay to Cass Railroad