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

If you can shorten the effective length of the lower strut rod without causing the lower control arm to bind throughout its full range of motion, you will gain significant positive caster. This can be done by cutting the rubber bushing a bit or machining the forward shoulder on the rod a bit further back.

Adjustable strut rods make this an easy update. Be sure to keep an eye on the general position of the front wheel in relation to the fender openings (front to rear) when performing this mod.