oipunkguy wrote:speaking of which, I've never really understood the reasons for the mistake plate on the early mosrites. To my knowledge the trem is routed into the body a little, but I don't know why a mistake plate is require for this???????? I'm sure Danny would know

It was the result of a design flaw.
Semie made those first guitars (the Joe Maphis model which became the Ventures model) with the neck glued in on a horizontal plane with the body. When he was ready to install the vibrato/bridge he found it set too high on the body which would have placed the strings about 3/4" above the fretboard. Having already built the guitars and ready for assembly the only solution was to complete them by routing out a recess to sink the vibrato/bridge down into the body. The mistake plate is the half moon black plastic cover surrounding the upper and back edge of the vibrato covering the unsightly recess channel.
BTW, woodchuck, you're doing a great job and it is a very interesting and unique project. It's a great learning experience to build your own guitar, isn't it?
