I have 275's in mine.

I Have 275lb 10in springs on 3850 Affcos mounted almost straight up and down on a Bobs Pro Fab front end, Bondo Bob recomends 250lb springs on A-body cars, i somehow got shipped 275lb springs BUT i had to move my lower coilover mount on my lower control arm inward some so the extra 25lb compenstaes for the inward movement of the mounting point. this is on a all aluminum motor, stock location. if i ever install the aluminum headed 440 then a 350or 400lb spring would be my choice. btw call Bob @ Bobs Pro Fab he full of knowledge on this stuff.

You made me buy 350s. My life would be cheaper without you in it

Torsion bar rates are at the wheel not with a 250 lb weight sitting on top of a coil spring etc. to measure lb/in. An example is it takes like a 600 lb coil to get a 350 lb "Wheel rate". Don't freak but Firm Feel has Wheel rates on their website for torsion bars.

But it is so fun spending your money!!

10-300 spring on the front of mine.....