I have a 72 chevelle with a 350 tranny, 3.73 gears, 28" tire. I put that into that speedo formula and came up with 2.69. On the small gears chart there are 2.67 and 2.71 as the closest choices. Both of those choices having different speedo gears. What would be the best guess and what color would these gears be? Would part numbers be asking too much? Thanks in advance for any help given!

Go to www.transmissioncenter.net and find the speedometer calibration link. They have gear colors, number of teeth, and charts for calibrating your speedo.