You know James, I dont know what kind of exhaust turbine housine that is, but I do know TURBO CITY has pre molded shields for some of the exhaust turbine housings, might be worth the call to see if they have one to fit your turbos. Might be a good idea to run those along with your shields. Also, tell you what, if you like, I have a metal break at work and hole punch, and just happen to have some SS sheet. I can make an identical set for you if you want with all the bends and stuff like that exactly the same.
You are in the right track tho, you need some good shielding, you have two chunks of cast iron heaters now so you need better heat dissipation overall to keep the engine compartment cool. Another consideration is the second turbo inlet tube (rear turbo) and the heat transfer to the inlet tube by running the inlet very close to the first turbo exhaust turbine housing. Something to think about when you design the inlets.