It can be done. You need a modified B20 oil pump,
B20 pan, custom intake, custom exhaust, custom motor
mounts, custom driveshaft, custom throttle linkage.

On a 122 with fuel injection you'll also need a
fuel pump, fuel pump relay, fuel return line, high
pressure fuel lines after the fuel pump, fuel
pressure regulator, modified fuel tank to have a
fuel return feed. You'll likely also want a surge
tank. If it is a fuel injection system from a 740
or late model 240 you'll also need to add an O2
sensor to the exhaust.

If you want a 122 with modern fuel injection, the
simplest way to do it is to put a B20F with K-jet
fuel injection and a distributor from a 75 240.
K-jet is a fantastic setup -- efficient simple and
reliable and volvo already did all the hard work on
stuff like manifolds and such.
chris