Well, you'd better be sure your present steering wheel really is 15" and not 14" before you order - better take a measure. If it is 15", the upper part of a 14" ends up half an inch under what you already have, should not be that difficult to estimate. If it seems to cover the instruments, take note that Moto-Lita makes a 14" offset, check out their website. That said, I doubt that there is a problem. I am 180 tall (=six feet) and had no problems with 14". However, when I fitted power steering the steering column ended up a little lower, and then the instruments were partially covered by the rim. So I ended up with a 14" offset after all.
Of course the steering will be heavier but as the 4/4 tyres are relativly narrow, you should be ok. On my Roadster with it's very wide tyres I was not ok, so I fitted power steering, but that is another story.
