A tool can be made from a discarded axle shaft or drive shaft. Cut off the tapered end of the shaft and remove the key. The other end can be turned down to fit a 1\2" drill press. Slide the pinion on to the tapered end and install a nut finger tight. The area of the front bearing can be turned down on a lathe using a cutting tool or Emory paper, or in a drill press using a file or Emory paper. The surface is not that hard. The dimension is only .0015 smaller than the area of the rear bearing.
For a description of the process go to the web site of the Santa Anita A's of Arcadia, California at
www.santaanitaas.org. On the home page put your cursor on "Technical Reference", my name will appear below, click on it.
A menu of articles will come up. Scroll to "Steering", and then to "R&P sets, Reproduction Blues". The article is a pdf file, you are welcome to download and print it out.
Tom Endy