Just to close the loop on this thread, the R975-C1 engine with its 5 broken connecting rods is now a display engine at the museum. The Sexton remains engineless.
A restorable Centurion is now my focus. The ironic thing is we have four Rolls-Royce Meteor engines in various states of repair here, leading one to assume we could make a good one from all the parts for a reasonable cost. But in reality, the cheapest option seems to be to buy a rebuilt one one from these guys for $10,000. And it comes loaded with all the accessories.
http://www.newenglandboatandmotor.co...gines-for-sale