I went through all that back in the mid-1960's! Trying to use an automotive tach on a slow reving tractor engine. Spring of '69 I bought a used distributor drive gear housing, a tach drive cable and a tach for a FARMALL 300/350 and installed it on my stage II Super H. Only took a couple hours to install.
Same thing could be done today also. Parts guy at my IH dealer back then had the drive gear housing set aside for His H but I beat him to the punch.