hey Alex

I would forget the leak down test if you don't have a compressor or the gauges, Do a compression test and that will tell you if there is a bad problem , they are like 20 bucks at a autozone type of place,

Be real careful you don't wreck the head gasket, the head will have to come off for that fix, and if the head is off and the oil pan dropeed, your more then half way to a full rebuild,
I have been looking for a spent 16v engine for some time now,
I want to rebuild it with some cossworth or JE high compresion pistons , Just don't want to rebuild mine engine yet, to much fun driving her everyday , maybe in a few mo. when the 911 is done,
Good luck and keep us posted!!
Dave

p.s im in woodstock in the woods with long twisty roads
and no cops=no tickets