I think the engine end fitting is a "universal standard" (I just swapped a Yam (metric everything) for an aging Merc (imperial everything) and the locknut screwed straight onto the tilt tube. Having said that, the engines were of a similar Hp. I think once you get above about 150ish Hp the steering gear beefs up to suit.
As Dirk says, your part number should be on the cable, of which at least a couple of digits will correspond to the length. If not walk in to your local supplier with the old one and say "one of these, but X amount shorter please" - they should be able to help!