Be carefull when fitting HD studs in the stock block without an external oiling system.
The stock blocks stud hole castings taper towards the center from either end so even though there appears to be plenty of clearance for oil flow it can actually be very restricted mid way up the studs.
The trick is to bore the stud holes all the way through with a 12mm drill so there is an even passage way.
I think I posted pic's of this in the Orient Express drag bike thread.
I also counterbore the top of the block at the outer 4 studs for 'O'rings to help resist oil seepage in this area which is common, especially with the use of a copper head gasket.
