So I ordered an aluminum water pump for a 1978 440 and the lower house is on the wrong side. I should have looked closer at the pics I guess but I am planning on going with an aluminum radiator too so would it work to just get one that has the lower hose on the driver side to match the pump housing? I'm also going to do a serpentine belt swap on the truck in the future, I don't know if that will matter though.

 

Sounds as if you wanted a housing for a 383. 400 were on the right side as well. As far as the rad goes, you may, or may not find the right one with a rightside outlet or at worse have one custom made. I assume you want a bolt in, no fuss rad. I got one from Champion for $179 that was a straight bolt in. The only issue I have with a right-side inlet is that it makes the timing markers hard to see as it gets a bit busy on that side with the rad hose.