We ended up cutting the flue loose at both ends then cut an angled end on the front and ground it smooth to fit in the hole. 2 guys got in the firebox and using a sledge hammer and length of pipe as a punch "double jacked" the flue out through the hole far enough to cut a hole in the end to put the clevis in.
As I said lots of swearing and grunting.
The last tube job was done by leaving the superheater flues in, except for those on the sides where they were removed to gain access to the boiler barrel underneath them. It looks like 6 flues were removed and re-installed without rolling and beading them. We debated pulling the petticoat pipe, but decided to try it without pulling it out. It was enough to get the hood and blower ring out from around the exhaust nozzle.
Having a roof over our heads is nice especially when the "gentle San Luis Zephyrs" come through at 50mph.