is there a Dorman replacement manifold for the vettes from Advance/Schucks etc etc?
Make sure they have an exchange policy and explain to the senior curmudgeon what you're doing. take em home and try. You may even need a vette manifold on one side and a truck on the other.
For longevity and less heat radiating into the cabin, Id definitely use a cast manifold, you could even have em coated to look nicey nice. Id do all your mockery and test firing before you get em coated though