Sorry, these parts will be hard to find on lil honda. The parts you need, are not cheap or common... Time to join the bidding war on ebay. One tank is at $100 and the other is still cheap at $46 ''at the moment''. Buy it now for $200 LOL!
A 4 speed speedo? That's going to be big bucks, if it's any good. You could get creative and install a CHP 4 speed ''inlay'' on a less expensive 3 speed version if you can find a good 3 speed version for cheap on ebay.
Good luck!