Internal Swap 242/231

So I picked up a 242 from a WJ not thinking about the speedo. I have a working 231 from my 1992 and was wondering if there is a way to swap the internals to get the 242 to work inside the 231 case? I know the cases are pretty similar but not 100%.

not possible, 242 is significantly larger internals

Thanks. Hopefully I can get it sold then