302 heads for 318

You'll be paying for heads with parts you won't exactly be using at O'Reilly's.

The valve springs will go away. You will need the matching valve springs for that cam. If you get rotator valve retainers with the heads (some have them, some don't), you'll want standard retainers to use the springs that go to your cam.

If you get a set from the bone yard, the faces of the seats on the valves are likely going to be pitted. They have inductive hardening, so the intake and exhaust seats usually survive and don't need more than lapping compound, but check them closely.

The valves that were in the used 302s that I built had quite a bit of pitting on the exhaust side and some on the intake. I would have refaced the valves, but the seat faces were pretty expanded from use, so I dumped a set of stainless valves in.

The valves that I got were standard stem and checked out just fine. The guides were in good shape. I just lapped the seats until all of the bright streaking on the new valves were gone. Sealed just fine.

When I did the valve swap, I lost the flat faced valve and it bumped the CC in the chamber up to 62cc. The advertised cc is 59, I think it's closer to 60.

When I put mine on, I had a problem with gasket seal on one side. I ended up taking them back off and having them squared up and cut .010". I'd suggest getting them checked out by a good head builder, even if you end up doing the work.