13's, stock '71 318 short block.

has anyone heard of a 318 HP head

Yes, the factory used the term loosely on there HP 318 4bbl. engines. It was a 360 head.

MoPar performance also sold 318 HP heads which were nothing more than OE heads with better valves back cut with a valve job.
They also sold "302" ported heads which were very good on high performance 318's. A better choice than a 360 head in most cases. Theres a time and a place for a 360 head on a 318.