[fostereast]

I think the biggest difference is in the robustness of a street solution.

For example: I know the old Cast iron v8's could overheat and be OK, many new aluminum headed engines warp when overheated. I don't know what happens with the reproduction aluminum heads and blocks used in Cobra replicas when the engine overheats; if things warp and seals are lost, some people may make a decision to use cast iron to reduce the potential problems.

There may be other considerations as well.