[mr0077]

Fred, I just went through that speedometer gear misery...all of my own making, though.
FWIW, in chasing down why my speedometer was reading too slow, I found out that Mustangs Unlimited (mustangsunlimited.com ?) listed the toploader drive gears in 6 tooth ($14.55), 7 tooth (steel, $42.60) and 8 tooth ($24.65), plus all the driven gears for 7-11 dollars. I got mi driven gears from a local Mustang shop (John's Mustangs) for similar prices.
Bob's table should tell you all you need to know to select the right combo. I got my cable and housing from Oreilly (60", $16)...good luck