what are you using in the rear? I would think you'd want to keep your front and rear ride frequencies within 10% of each other. assuming 3400lb with driver and a 55/45 weight bias for my /6, no PS/PB/AC car, I get about 1.31/1.46hz front and rear if I get the 130 lb/in rate 6 leaf 340/360 spec springs. are you running circle track springs then with the big t-bars? was temped by the price of the speedway 175 lb/in springs, but figured that would be way too stiff and unbalanced with my .92" bars
https://www.speedwaymotors.com/Speedway-Chrysler-Type-Multi-Leaf-Spring-175-Lb-Rate,3526.html