Make at least one more forum post and you will have access to the private message feature. Drop me a PM, and I will be glad to make arrangements with you to modify your engine block. The job takes approximately 4 hours to do, as I demonstrated at one of the annual "homecoming" gatherings the forum has, a little over a year ago.
Here's the seal you need:
https://www.zoro.com/skf-shaft-seal-3-78x4-34x38-crwa1-nbr-38647/i/G9397674/Jerry
P.S.: When a 216 quits leaking, it's empty- - - - -pour some more oil into it- - - -just like a Harley Davidson motorcycle!