Marine blocks can be nice just watch out for the crusty and corroded ones. The Chris Crafts had both open and closed loop cooling systems. The open loop cooling system cooled by using the water boat was being run in either salt or fresh and the closed loop system by antifreeze. Saltwater heavily corrodes these blocks after time. I had a few myself as they were not well known about and cheap at the time. A good 427 marine block is worth $1500-1800 at best today. With all the new FE blocks coming out and I'm sure even less after a while. Pond MFG is the latest offering at $3000 and the Genesis for $3500 but both require some machining before building. Even before the Shelby block first came out the 427 blocks went way up in value no matter how good or bad the block was. I've seen NOS sideoiler blocks going for over $7500+ and still up there today. The 427 marine is a nice drilled centeroiler block cast as a sideoiler and most have part of the sideoiler hump shaved to clear the Chris Crafts motor mounts. I don't think the ones in the Trojans had this problem. As the sideoiler galley is not drilled it's really not an issue. You can still find nice production car std bore centeroiler blocks for $2000 and there were two just sold last week on ebay for $2000 each. JMO, G.
ps. check the guys at www.fordfe.com as well.