When I worked in M/C dealerships in the 70's, mostly Kawasaki's, we had to do a lot of single cranks. I had a guy I sent them all out to in those days. Also did a lot of other 2-stroke cranks, bultacos, DKW's, and once in a while had a twin or triple crank to do. A llot of those rod kits and big end bearing are no longer available parts of the old stuff from the 60's and 70's. I sent all that work out, like I did with cylinder boring and other machine work. You can do them with a small press, 12 tons which you can probably make up easily with some Channel iron, and a hydraulic jack. You need to make a fixture for truing the crank, will need a dial indictor, big lead mallet for smacking them and making them move. Definatly a art and learned process. I'm not sure if they have them in Japan, but in the states Harbor Freight has a press that comes with all the press plates. We used to straighten fork tubes on the press all the time too. You need a few vee-blocks for that.
Sounds like you are doing OK, hope you are well and staying low profiles on message boards.
Debrie from your earthquake is now reaching the shores of Northern Oregon and Washington. A lost boat just washed up on shore a few weeks ago.