360 heads on 318

If your doing on the cheap, the 360 heads will do OK and fine. It is alot cheaper than porting 302 castings. But that would be best. Not cheapest.
The thing with the 302 is not port size but speed of air flow (With fuel of course) and valve size that would work best for the intended purpose.

(Again, if on the cheap) While looking for a higher performing engine, you'll want a decent stall converter with a decent sized cam to get those 360 heads to work better. In this arena, streetablity starts go away some.