Sounds an interesting house John .... If someone had a deco house I wonder if just removing the original windows, having them blasted and galvanised then painted and replaced might work.
There were firms who would draw-form aluminium guttering to match cast iron profiles on site ... the ali comes off a roll in the truck so can be formed to any custom length thereby eliminating joins ... presume they still exist.
Guess fly-ash itself is now pretty much a thing of the past with the changes in power generation .. the world turns.
K
