That speedometer will work. All the sensors work the same. That's the only bit you need.
Full-width throttles are very hard to open. All throttles come apart the same way. You remove then from the handlebars, then look inside. There are normally three barbs that lock in when the throttle parts were pushed together. sometimes you can use brute force to pull them apart. Sometimes you can help it by inserting thin blades under the barbs. When the thing pops open, the spring might jump out, so don't do it in a messy garage. Reassembly is very straight forward. You just have to preload the spring by winding the throttle about 30 deg past its zero position then push it back together.
What's inside is very simple. The hall sensor is fixed in the non-moving part in a slot. The two magnets are at the end of the bit you twist. Often, there's a bit of grey iron linking them.
