Fitting V70 XC + 740 driveshafts?

My 1998 V70 has a common driveshaft problem, with the center bearing broken. Strangely, the bearing isn't replacable (undemountable), so another driveshaft is needed. A new one costs 1400$, and used ones are rare...

My dad had the idea of taking the middle of a 740 driveshaft (with center bearing) and having it merged with both ends of the V90 one (hope I'm reporting his theory well here). He knows a driveshaft specialist that could do the job well.

Anybody tried something like this? Any risk to damage the car or affect performance?

Thanks,

Th.