thinking of buying a car with an engine conversion with a 4age in it just want to know how you can tell if its a bigport or a smallport 4age as the owner doesnt know either?

If you can see the top of the sparkplug leads then its a bigport, Unless it is a smallport without the top cover, A bigport will have a smooth intake manifold with tvis, A smallport will have a ribbed intake.

easiest way to tell is the bigport has 8 runners and the smallport has only 4

incase you don't know runners are the tubes that go from the intake plenum to the intake ports on the head