Best Torsion Bar Size for 65 Valiant Convertible Slant Six

Hello All,
I'm trying to tighten up the suspension on my Valiant.
It has the original 880/889 (622/623) .83 torsion bars installed.
I want the car to ride firmer but not like a truck or performance suspension.
I was thinking about installing the 1.03 bars, but from what I understand it may make the suspension too stiff.
What would be the best choice to firm up the ride?
The 892/893 .87 Torsion bars?
Thanks