Tachometers, red-line, etc.

[PB Schechter <pb@domain.elided>]

All this talk about what RPM is necessary for what speed is relevant
to some investigation that I have been doing.  I have a 304 in my
'65 Travelall, and the book says max RPM is 3900 (but the plate in
the driver's door says max HP--180-ish, I think--is at 4200 RPM!).

In any case, when I was in the local junkyard, I saw an IH cement
mixer (without the cement mixing apparatus) that had a tach in it.
I investigated, found that it was mechanical, pulled it out, and
bought it.  It is a 4,000 RPM tach, which I though should be perfect
for my 3900 red-line engine.  Now the question:  It has a cable,
similar to a speedo cable, the was screwed "somewhere" (it was too
hard for me to see--I could *just* manage to get my hand on it, by
following the cable) at the crank output/tranny input.  Is my T'all
likely to have the appropriate gears to match with this tach, or
am I probably out of luck?  (It's not easy for me to see back there,
without a ladder or stool or something to stand on; my T'all is 
4x4, and too high for me to see into very well....)

Thanks in advance.

PB Schechter
pb@domain.elided