Broken speedo drive on early 915

[Roger 911]

I was trying to detach the speedo cable from my '72 915 and the threaded part cracked off of the front cover. I realize this sucks in many ways. I need to remove the engine/tranny to fix some other transmission issues I have (different thread). This creates a series of questions.

1. It would appear I have no choice now but to cut the speedo cable to get the engine/tranny out. Suggestions?
2. How difficult and/or expensive will it be to get a replacement front cover for this trans?
3. Would this be a good time to consider ditching the early 915 and replacing it with a later aluminum case 915 and an electronic speedo?

Thanks.
Roger