I am in Brisbane with 5 finnies in all sorts of condition. However, as you said, mine and everyone elses I know are all cracked too. So I think good wheels may be like hens teeth. However, I have recently bought a 300SE coupe project that I think has a good wheel. I am not likely to use it as I have a Nardi wheel, so I may sell it. Trouble is, I don't pick up the car for a month so you would have to wait.
You could also try ringing Pearlcraft to see what it would cost to get your wheel fixed properly. They don't just do pearl wheels.
I have played with modifying steering wheels for my V8 project - have a look at this photobucket page of mine:
Finny build-up pictures by drew56cus - Photobucket
I made my own adapter for the Nardi wheel first by drilling out the splined part of a wheel identical to what you have now. But it looked clunky. Then I spliced together the top part of a W108 column (that your new wheel would fit) as it is shorter, onto the bottom part of a finny column that matches the firewall. I used the 108 internal shaft after tapping i on the ground a bit to make it a touch shorter (it is collapsible). Not quick but it worked. But you end up with the uglier 108 indicator switch which would not be compatible with your wiring (it worked for me as I used a 108 wiring loom).
As to your options, here is what I think (without having a later model wheel in front of me)
- I don't think you could cut off the older wheels base and re-use it as it is all cast as one piece?
- I think the diameter of the old and new wheels where they mount to the column is different? So it may look odd if you mix and match those bits
- I would try initially to post the good wheel for sale on ozbenz with a good price - equal to what Pearlcraft may cost to fix your one. It is concours season and you never know if someone wants to complete their resto with a great wheel?