R&P change means change speedo?
 

Been trying to figure out how far off my speedo is and remembered something. The 912-6 originally came with a 923 tranny, which has a 7:31 ring and pin. I changed to a 79 sc 915 tranny with a 8:31, both electronic speedos. I got the tire size about the same.

If I change to a later sc speedo, will this fix my speed error?

Thanks!