Hello. Can I use an 800 series in place of a 400 series behind my 140
HP 3Litre?
I know it's not advisable to go the other way...
But will it physically fit onto the upper? The 400 is a 1.65 ratio,
and the 800 is around 1.77, so i realize I would have to prop
different, but that's not a problem. My math says going from a 19
pitch to a 21 should do it. tks.

btw, I think I'm using "upper" incorrectly, I mean will the whole 800
series drive attach to intermediate hsg... tks.