So....... I tried the lime away which did dissolve some of the calcium deposit but after three weeks of applying it in the evenings I got impatient and just scraped off all the deposits in about an hour. The larger issue I now face is that the cutlass bearing has developed a vice like grip on the prop shaft.
I didn't notice it until yesterday after I had finished adjusting the valve clearance and re-torquing the head. I ran the engine to warm it up and to see shat my motor sounds like with properly adjusted valves, but when I threw the transition into gear the engine came to a very abrupt stop. For a while I thought I had some kind of issue with my transition, but I eventually disconnected the shaft coupling from the transition output flange and it was clear the heavy friction was in the cutlass bearing and not the transmission. So either the calcium deposit hardened over the winter and is causing increased friction, or the lime away swelled the cutlass bearing.
My next step is to try and pull the prop shaft but we probably already know how easy it will be to persuade the shaft coupling to come off the end of the prop shaft.
I am pickling it in pb-blaster right now so I wont know for a few days, but if that doesn't want to come off I may try and make a jig (poor mans Strut/Pro) to push the cutlass bearing out with the shaft still in place.
I'll keep you all posted on how it comes out. (or doesn't lol)