[metromizer]

I wouldn't discount a vacuum gauge for the VW engine. I'd use a metal line the length of the car, and short sections of rubber hose only where you need the flexibility. I have about 6' of rubber line in my metro's vacuum gauge line, and it works fine. I did have to buy an in-line vacuum orifice (the small one) to damp the vibrating needle, Balcamp brand from Napa Auto Parts I think.

I've used one of those speedometer cable gear boxes on a Nissan truck years ago. They are ok, but you need someone to initially set them up for you, someone who has several gears to choose from. I did it before GPS, the automotive speedo calibration shop i took it to had an in-ground roller set up. An inexpensive Garmin GPS can double as a speedometer, I do it when playing with VW's. There is a dashboard setting that shows MPH in real time, that I've used on rallys and racing at Bonneville. If nothing else, borrowing a GPS could help you cross calibrate your speedometer, masking tape arrows on the glass noting 25, 40, and 55, and 65mph.