Plan worked. Got about 3 hrs in today.
Worked on the exhaust pipes but mostly the transitions right out of the turbos. I calculated that I needed eight .40 pie slices out of the 5" to transition to 4" dia.
It was a little difficult as it was a short transition and ended on a curve. Lots of extra stresses in the stainless at the curve. Was able to sort of pull it all together with big radiator style clamp and get her tacked. Bigger news for us is that when I held it up to the turbo it cleared the dry sump pump and pulley.
Not perfect but close enough.
I can work it a little more round when I tack the 4" to it.