I dunno, Thai....
You may be the first. I have never heard of that one.
Rule of thumb has always been that the transaxle, ring gear and starter go together as a set.
I have run a 5-speed flywheel with a 4-speed ring gear on a 4-speed transaxle with 4-speed starter, mainly to get the extra 15mm of clutch diameter.
And I have heard of the opposite, as well, putting the 5-speed ring gear on the 4 speed flywheel to use on a 1300 converted to FIAT 5-speed.
I suspect that the difference is that they changed the C-to-C distance and/or tooth count.
I guess you need to head out "Where no one has gone before" (Star Trek) and find out.
Ciao,