One little note on offset bushings...

Did your mechanic mention he could get more caster on one side only
but not the other? So he adjusted to the lowest side?

For example did he get 2.5 on the right (pass)
but only 1.7 on the left (driver) and adjusted to 1.7 1.6 ?

In this scenario, the front box of your frame is pointed slightly to the right... so you can't dial in much of any caster on the driver side if the box (frame) is diamond to the right...

vice versa if the front box is pointed (slightly) to the left...
you can dial in a lot on the driver side but not on the pass side...

Chrysler frames are notorious for not being perfectly square from
the factory. Let alone if they are 45 years old and have been driven, bumped, hit etc...

Further, the spec on the old frames is a quarter of an inch..
(Which is a country mile by today's standards)

This is one of those instances where a non square front frame will show itself.... Don't worry, you can still align the car but you'll never get max caster with stock arms and offset bushings.. you'll have to go to the
aftermarket arms...

Even with aftermarket arms, usually one side will give you noticeably higher positive caster ratings than the other...this is a sign that
the frame is pointed ever so slightly to the highest side...

There is a lot of play built into the new arms you should be able to get
what you want...

Best of luck to you....