as I wouldn't think that a string of bytes making up a 7-digit and a 3-4 digit (depending on whether I would make the trip odo either 3 digits, 0-999, or 4 digits, 0-999.9)
The schematics I have in the books use a combination of the LM2917 (frequency to voltage converter),...
call and get a 7-8 digit LED made for the odometer
either the leading or trailing digit blank
with an RS232 serial port
will be run off of an aftermarket ECU known as the MegaSquirt II.
However, this adds wiring to an already overcrowded under-dash wiring harness