There is nothing really wrong with a kingpin front end - manufacturers mostly switched to the ball joint front ends because they worked as well but were cheaper and simpler to make. Rebuild kits are still available for the PV front ends, try www.GCP.se, also I see them go by on eBay (English Quinton-Hazlet stuff) occasionally. The PV's front end is wonderfully precise with almost all metal bushings with no slop, and precise adjustments with the threaded and offcenter bushings.

I've seen entire other front crossmembers put in a PV before, but you'd really have to know what you are doing with the steering linkage - the angles and arm lengths are not amenable to tinkering. All in all I'd say leave the front end alone and rebuild it if worn.

B20's and M40's fit in fairly easily on B16 engined cars. I've only done the B18-to-B20 swap which is a 100% bolt in affair, but I don't think the B16 cars are too much harder. Issues would be the lower radiator hose (wrong side), 6 volt electrics vs. B20 12 volt starter/alternator, clutch linkage (I think they are not quite compatible with B18 544 bellhousings - and if your donor vehicle is a 122 or 144 it will not have the mechanical clutch linkage style bellhousing).

With the increased HP of the B20 in the light PV you will next feel the pain of the very low gearing - B16 engined PV's had 4.56:1 rear ends and you'll wince everytime you get on the freeway and over 65 mph unless you either lower the rear end ratio or fit an M41 OD tranny. But the OD tranny involves cutting and replacing the tranny tunnel to make room, not a trivial task.

Cornering is vintage 'heeling sailboat' scary unless you get some IPD swaybars, which then point out the failings of the skinny tall original tires.

PV's are great cars. I've owned many old Volvos's (140's, 1800's, and 120's) and my PV puts the biggest grin on my face for some reason.