the speedo sender out of any 71 series datsun/nissan box will fit. so pretty much the sender from any nissan 5 speed box from the 70s-90s should work

speedo cable from a 200b will also be long enough to work with the stumpy box, thats what i used in mine and for another L series 1200 using a stumpy box

i cannot vouch for how accurate the speedo will read as that will depend on the diff ratio and tyre size and what not