Oil leak behind the cam

OK, that part about 1 side then the other makes sense.

Good observations on the actual timing. Well, yeah, your cam timing could be off. 1 tooth off is 14-15 degrees. Or the indexing could be off on the oiling holes through the #2 and #4 cam journals. No way to know without timing the cam... assuming it was not done.... which you can do with the timing cover on. How assembled is this engine and is it still on the engine stand? Is the intake still off? Oops I see it is on.