A carb may be able to perform as well as FI at WOT but I'm
planning on installing FI on my 164 to see if I can get the
fuel economy up a bit.

I think the best way to go is to go with D-jet hardware but
use an after-market FI computer like megasquirt. Everything
would look the same from the outside (Except for a vacuum
hose running into the wire harness for the MAP sensor on the
MS brain) and the wires would be mostly the same, but it
would be programmable and adjustable to suit the specifics of
that motor. With d-jet the only option is to fiddle with
the mixture and that adjusts the mixture across the whole
range.

FI on a 122 is an extra bucket of worms due to things like
gas tank fiddling and such but probably not super hard.
chris