I would say that the GT-40 heads would work best for that application, and would be great if you ported both the lower intake and the heads. If anyone else has a different oppinion please chime in.
if you dont want to shell out the cash gt-40 heads, but if money isnt a issue the get some afr 165cc heads and a custom ground cam. if not e-303 or b-303.
I agree - GT40, GT40P (with new P headers), Windsor Jr, Windsor Sr, GT40Y or GT40X heads will work nicely with the intake in stock form. If you use TW or AFR heads, I suggest getting the Explorer lower intake ported as the Explorer intake flows about 40cfm less than those heads.