Check the heads, but also make sure that:

They don't bottom out on the dowels. Drop them on without gaskets to make sure.

Run your intake and exhaust bolts and any exterior bolts (Alt. P/S) into the holes before you install.

You have the right head bolts and washers along with the gaskets.

You have the right spark plugs.

After putting on the rockers, roll over the motor and watch the valvetrain. Make sure the pushrods clear the head, and check the rocker to valve tip pattern.

Some of this should not bite you, but these are some of the things others have asked about after installing out of the box....

I hope that John or someone else would provide a better checklist, but there are so many little things that a knowing eye can see that such a list could be pages long. This would apply to even stock heads, BTW.