(G) fitting an uno mk2 turbo speedo head to uno mk2 70s

hi everybody i've bought an uno turbo speedı head from ebay now i'm waiting for it but the question is i'll connect the cable for the tachometer but what about the speed? because you know at standart speedo you can only have 200km/h at maximum but turbo one has 240km at max so will there be a problem about it or turbo's speedo is different inside from the standart uno's 200km/h speedo?will i read the speed right?and also do you have any suggestions regarding oil temperature and oil pressure gauges as i only have an oil pressure warning light thanks.