Help Please
 

Well i have a classic VW beetle Working on restoring it.

I picked up a used engine to put in it. 1600cc single port, late 60's year.

Well cleaned her all up, cleaned carb etc... she runs nicely, BUT on the right side of the engine I a leaking oil from what looks to be between the top main head and the two round cylinders below. I thought well maybe the nuts on the engine studs need to be tightened some. Well took rocker assembly off and checked the 4 bottom nuts all of the except the second nut from the rear was loose, but further looking the whole stud was spinning when I tryed to snug it up. It would not tighten up (the other 3 were nice and tight) Could this one not tighteing up cause my leak? How the heck and I going to fix the case to be able to snug this up if it is the problem? My budget is very limited.
The motor is out of the car and on my bench. I have to fix this problem, motor seems to run nicely, I hope there is a easy way out of this.

I hope some one can help me out

THANKS!

George