Sean,
Glad to see that you are going to be doing injectors again, I have already PM'd you for prices and particulars.
I see that you guys have expressed an interest in a lapping plate or a surface plate. I have a set of books that give instructions on building machine tools and one of the projects for the mill was a set of homemade surface plates. Basically he took 3 pieces of plate glass and set them in beds of bondo so they would have 100% surface contact, and using valve grinding compound, alternated the 3 against each other. You can get them to dead flat, but it will definatley take some time. After building a couple of this guys designs, I think that If I could find the surface plate for under 250.00, I would buy it instead of making it, but if anyone is interested, Ill scan and email/attach