Thanks for your quick replies. I also found some info on the net about doin it cold. ie Set engine rotation so lifter is on heel of cam for each respective valve, then adjust until no play in push rod (can use .0015" feeler gauge instead of testing by rotating push rod), then tighten 3/4 of a turn more. I need to do at least an initial set this way, since I have just replaced one head and everything is way out.

Does this sound OK. I'm not too keen on getting oil throughout my boat, and I don't have spare rocker covers.

Cheers