I swapped out my old (maybe original) stock 4 leaf springs for new 440 springs +1" from ESPO (
http://www.springsnthings.com) on my '68 Charger. The car was originally a 318 car, and the PO put in a 440 but did not change springs. I also had old shocks, and installed new Monroe sensa-trac shocks too. I am waiting on new bigger torsion bars, front and rear sway bars and front shocks to make final adjustments on the front and then off to alignment.
I know its a Charger but hope the measurement differences help (275/60/15 rear, 235/70/15 front):
Before After Difference
Front Bumper 19 7/8 19 1/2 - 3/8
RF 25 1/2 26 +1 1/2"
LF 25 1/2 26 3/8 + 7/8'
RR 26 1/4 29 3/16 +2 15/16"
LR 26 1/4 29 +2 3/4"
Rear Bumper 25 3/4 29 1/8 +3 3/8"
Before
After
New Springs and Shocks
