I think adding an adjustable PV is less complicated then replacing both rear wheel cylinders, and has a higher probability of a successful outcome. But YMMV...
Depends on how you add the adjustable valve. I wouldn’t put a big loop in my brake line so that would mean making new brake lines which is definitely more time consuming than swapping the wheel cylinders.
I have an adjustable valve installed on my car because I run rear disks and wanted to be able to adjust the bias, but I also made new lines for it.
Some folks just prefer things to look more original. Either way you’re adjusting the line pressure to change the bias.