i finished my little ashtray -> tach project. i installed a tiny tach + hourmeter into a spare ashtray to leave the dash of my 56 unmolested and for easy return to OEM for showing. just need to tack the gauge flush to the ashtray with a little epoxy and pop the whole assembly in (then wire of course). i thought it came out pretty well.

pic here:

http://i1234.photobucket.com/albums/ff419/tomctomc/tinytach.jpg