When should you upgrade torsion bars?

IM upgrading my rear springs to Espo’s 6peaf +1’s and I have been reading a lot of the guys that go with 1” torsion bars. Is that only for big blocks or is that wise for a guy like me who has a build 360? 73 dart swinger... let me know what your thoughts are. Wondering if it is worth it to upgrade while I’m doing the rears or if it will just make it super stiff and undrivable.