High Oil Pressure is normal at startup, at least mine has always been that way. As far as the leak goes, my first step would be to clean the block up, and try to see where the leak is coming from. Also try a cooling system pressure test, if the leak is as bad as it sounds the sound of the hissing air should help you pinpoint the leak. I've never had the "pleasure" of doing a head gasket on my D, but judging by the overhead cam setup, it dosen't appear to be a fun job....but on the other hand, its a lot cheeper than an engine block. Don't give up hope, Ive been there too, heck I had the motor mount bracket fall off the side of my engine block, (thank god I was able to find a welder who could fix it). Good luck, Andrew 4194