sounds odd as the tacho/hr meter is a kubota option and fitment on the b7100, the tacho does have a straight connection, and yes it is a tight fit to be honest, but if you have the correct cable it will fit in and reach the tacho drive gear on the engine .
if i recall correctly you need to remove tank first to be able to get it fitted or remove the dash screws and move the dash up abit to give you enough room to work in.
once you have the cable fitted to both ends you can then refit the tank and carefully move the cable to enough for clearance etc.
It sounds a bit mad but it does workout .
Are you sure its the correct tacho/hr meter and cable you have.
There is not alot of space behind the dash panel anyway so doing any work in that area can be a challenge, as i said, i allways took of the tank and battery to get maximum working space etc.
good luck with it, maybe some pics from you fitments would help us guide you better to a successful fitment.
rgds
rob