[Vwdiesel] More Dasher?

[William J Toensing]

Went to my '81 Rabbit that someone stole the head from, & found it had two 12 mm studs I was able to salvage. I found the studs to be 5&1/4" long. The 11mm bolts were 3&11/16"  long from the bottom of the bolt head to the tip. The crack  is 3/8" deep, then turns 90 degrees. Since the bolt hole is 1&3/8" deep, I wonder if hole could be drilled a little deeper & tapped for a 12 mm stud & save the block. If necessary, I think I could salvage the block from the Rabbit & rebuild that engine. To switch a Rabbit diesel what changes have to be made. Does it take a different fly wheel, clutch?
Is ARP251-4701 the correct length for my non-turbo '81 diesel engine?