68 rear spring ?

[earl87gta]

The 68s had nerrow springs in the front 2.5 in stead of 3 like the newer trucks and the rear had 3in wide. On the front Im running 6in springs with a 1in 0 rate.
On the rear I have a 6in blocks and I want to get rid of the blocks and level it out with the front I was going to have DIY make me a shackle hanger for the rear 3inW spring but I still need 3in more to get were I need to be. I can use a 0 rate for 1 in but then I have to come up with 2 more can I use leafs off a mewer front end to add leafs to my rear stack. I only have 2 in the stack right now so adding some will not hurt any. Seams like I remeber reading some were that the conture of front and rear springs are diffrent so you cant do this becuse over time it will cuase a spring to break do to stress points.
Any one have any input on this or should I just replace all my spring hangers for the rear and go to a 2.5 wide spring like they use in the rear now.