I'm not sure that they do still have 164 lines. When I did mine I
first called IPD and they said that they stopped selling them.

I don't remember the name of the fellow I spoke with. He said that
they had an instance of the brake line snapping at wheel lock and
full suspension travel. The failure was at the point where it screwed
into the brake and it failed apparently because the flex line is a
little too short and the part that threads into the brake itself had a
thread adapter so it was twice as long as would be expected but rigid
and not terribly strong where the hose thread screwed into the volvo
thread adapter. Plus it would be prone to fatigue as it gets jerked
back and forth. I hope nobody was hurt. Of course, I've had total
loss of one brake circuit on my 164 and the car did stop; not as well
and it pulled to the side but it stopped and I knew instantly what had
happened.

bad ascii illustration:
hardline on body -> steel hose -> rigid wacky thread connecter -> rigid volvo thread adapter -> volvo brake caliper


It's totally reasonable that IPD stopped selling these if one failed.
I think that there are places that will custom make a set of steel braided
brake lines if you take them a set of rubber lines as templates. I'm not
sure of the cost, though.
chris