I'm not sure he claimed that the 13:1 engine ran on 89 octane.The 9.5:1 engine runs on pump gas. Just for reference my old 512 BBF w/FordMotorsport A-460 heads and 10.2:1 comp. made 710 HP at 6,000 and 661 trq. at 5,000. (I know it's a different animal, but just shows what good airflow can do for you with out alot of compression)
700 HP out of a 468 is 1.5 hp/cu.in. Can you get approx. 350 cfm out of those oval port heads? If you can, his dyno numbers aren't out of the question?
I'll ask a couple of guy's I know today what they got out of the stompin 470 BBC they built a few years back. I'll get back to ya.
Sleeper CP
Maybe if Geoff ported his heads