Help with speedo!

Hi, the speedo (it is scaled in km/h)on my gtv2.0 is no t working fine, it reads the speed but doesn`t count the kilometers travelled. I will try to have it fixed but I`ve been offered a solution that I am not sure if will work.

I`ve been offered a 1983 gtv6 british version speedo (the primary scale is in mp/h but has the km/h conversion) but I am not sure if it would work with my sending unit, and if it works, if the speedo will read accurately the speed and the miles travelled.

Does the sending unit on the gtv2.0 (alfetta gtv) is the same for the gtv6 considering they both have Veglia Borletti Electronic speedos, but they have different scales (one in km/h and the othe one in mph)?

Your help would be very appreciated as I need the speedo soon!!!

ps. I`ve reached the factory but paying 270euros including shipping for the speedo is way out of reach, 100 euros+shipping for a speedo in Italy is also way out of reach, and I can`t find one here in Peru!