Hey, welcome to the club haha j/k. I just recently installed a speedo on my big red. You can use any speedo head pretty much, depending if you want it in mph or km/h. The difficult part is finding the speedo cable and gearbox for your specific bike. The best place to get most of everything is ebay. They pop up on there from time to time. Do a search on here and you will find some more info. and part #'s on speedo stuff.
1985 Yamaha 225DRN w/OEM headlight guard, footboards, front rack, rear rack, work light, brush guards and trailer hitch