Cranks have never been a problem before when we drill and debur the cross-drilled passages for better oil flow. I agree with Tyler about the drilling, but Rick made a VERY important point. You can't just drill freehand into the crank. Not accurate enough. Above 2000rpm it will start showing any misalignment and the vibration will increase with rpm. A lathe is a MUST! If you don't have one that can handle it, the cost for farming the work out will probably make you just go find a Voyager crank. I shop "Kawasaki Voyager 1300" on eBay all the time and have seen them for $100-$150 often in the last four months.
There's one from a seller I have been happy with several times, and this one comes with the large magneto at one end and all six rods, all for $50 plus about $60 for shipping. All under $120. Right now there are a total of 9 cranks, most from '84 Voyagers. prices range from $50 to $200. Most under $100. To set up in a lathe and do the drilling and tapping will cost around $100 in most commercial shops.