Have you married a Beta 43 to a Volvo saildrive before?
I have a friend who considering the exchange his existing Volvo 43T, for a Beta 43, but wants to use the existing saildrive. Is this economically feasible?
Until you confirm I must assume that your friend's engine is the Volvo 2003T. If this is correct the largest engine that is likely to fit in his engine compartment is the Beta 38. The Beta 43 is physically much larger than the 2003T.
The other issue is that the 43 has much more torque than the 2003T at low speed and thus is likely to shorten the life of an old saildrive. What boat does your friend have? If you let me have the specs, I can run some prop calculations for you.