Any way to get more caster adjustment without newer adjustable CA?

Use the offset upper control arm bushings.
FYI they are 38.99 plus tax at O Reily's Auto

Moog K7103 : Front Upper Control Arm Offset Bushing Kit 1960-76 Dodge/Plymouth Car | JEGS

My cost at O'Reilly is $34.70 as a wholesale customer. I bought all my parts on Amazon for a ton less. These bushings are $24.02 with free two day prime shipping since I'm a prime member. Man, I love Amazon.