I have a sparco D shape on my '69 142.The way I did it was to fit a removeable hub kit. you pretty much have to plan on not ever putting on the stock setup again unless you replace the upper sterring column. Anyway if you want to proceed I bought a sleeve style quick release wheel hub and it comes with a weld on spline. I got a nice one so it cost 55 bucks, but you can get the nob style ones for about 30. After that I bought the momo adapter for 40 bucks that fits the quick release hub. Then your set to fit any wheel with the six bolt italian pattern. Since the spline is weld on it won't ever come off and I imagine that if I needed to put a new steering column in I would have to cut the upper half in two to get it out.

Goodluck, Aaron