How much hassle do you want to go through? Remember that everything after the M40 / 41 / 401 was designed for use on the later OHC engines which were tipped over as opposed to being straight up and down so you do have a match up problem. That could be fixed with the very rare B20-M45 bellhousing. There was discussion on this topic previously:
https://www.volvoforums.org.uk/showthread.php?t=285670
If you check around, the M47 does not get much love. 'Internet' opinions suggest that it is less durable than the M46. If you want a true 5 speed, you might want to consider using one of the T5 variants. You would have to search for one with desirable ratios (they are not all the same). T5s are much more common in North America. If you search you will find that T5 installations behind a B20 are not completely rare. It does require an adapter and a different clutch. I expect that the B20 bell housing will fit the B30 so there is probably already a completed path of discovery for the conversion. Better to let somebody else discover all the problems first.
On a B20, the T9 is probably an even better option than the T5 (better ratios). However, the T9 is very rare in North America (when was the last time you so a Ford Merkur?). The XR4ti was rated at 170 hp so the T9 should be suitable for a B30.