Aluminum or cast iron intake?

I have a small crack in the exhaust manifold on my '75 Duster. I'd like to get a used intake/exhaust unit to swap in. I have access to an aluminum setup from a '76 Dart Lite, but would like to know if it is prone to any problems, seeing as how there are two different metals involved. Or should I stick with an all cast iron unit? Performance & weight isn't a consideration, - cost & reliability is. What would be a reasonable price for each type? Thanks in advance, - Dale.