You might consider some Super Stock springs.

You could have a shop that rebuilds springs re-arc and add a leaf of two the springs you have.

I remember back in the day you would see cars with them and the rear valence cut for clearance. I don't think you want that "vintage" look. Super stock springs are not a good idea for a street vehicle. My first Challenger had air shocks and the upper shock support was cracked everywhere. Re arch the springs would be my choice.

I remember with my Challengers using a 15x10 wheel with a 4.5" backspace. N50X15s of various branding- Kelley Supercharger- Pro Trac. I had air shocks and made sure to keep the rear high enough to not have the fender lip damage the beautiful side walls when going over rail road tracks.

A wee bit off topic but my '83 El Camino came from the factory with air shocks and all the mounting points looked great last time I changed shocks. Over 200,000 miles on that one......

It's also irrelevant. Your Elco doesn't even use the same style rear suspension. Is not made by the same manufacturer and was designed by the factory to use air shocks.

If you're set on air shocks, Gabriel HiJackers was the go to back in the day shock.
Best is ew springs and longer shocks. Talk with a knowledgeable spring shop and have the height (lift) and current center to center of the bushing dimension. Let them know the ride you desire (race or comfort). It's possible to re-arc but I've found that to not last. SS springs may not give you the "look" you want, and will likely end up with an uneven height across the rear. New properly set springs are really not that expensive in the big picture.
Lifting using pressure can hurt the body end mount of the shock over time, and amount of lift. Doing it with springs does not generate more forces on the uniframe.

I love the old look.

And this one.

I had N50 15 Mickey Thompson set up like that. But even with air shocks we rolled the lips.
Wood baseball bat stuffed between the tire and wheel lip held by friend as you drive away slooooow.
I knew quite a few guys who also did the same thing. Even used my bat.
They thought I was a genius.

Regarding the snipped comment above, 10" rims will fit inside the wheel lip if you move the leaf springs in and use the correct backspace wheel. I've got 10" rims with a 12" wide tire under my Challenger, all inside the wheel lip opening.

This but please move both front and rear.
I have seen guys just do the easy part. Move both.

This is what six may be referring to

http://www.2040-parts.com/nos-mopar...ackles-for-super-stock-springs-i1302177/

just grabbed this not for the ad, but the pic.

IIRC, E bodies have splayed leafs, so the front hangers are already in compared to the rear.

The offset shackles just moves the rear in and makes them more parallel. Not sure why that would be an issue.

It isn't a big problem to change an E body's splayed mounting to parallel and it does provide additional clearance at the rear spring segment, which can help with fitting wider tires in the wheel well. Many drag racers do this. However, the splayed mounting does provide benefits in roll resistance, lateral stability, and rear steer characteristics. That is why the factory went to the splayed mounting arrangement in all cars eventually. The E bodies started in 70, the B bodies in 73, and the F bodies in 76. A bodies never got splayed mounting.

On my car, I did move both ends of the spring in an inch to both provide clearance and retain the design characteristics.

Saw a hi-jacked beater/period modded Trans-Am in a show on Netflix yesterday, and noticed that it had small brake/taillights mounted underneath the car on the shock mounts. ---As in, the back of the car is jacked up high, so they put a couple small lights way under the car where you can see them from behind... Anyone ever seen this this done back in the day? I'd never heard of it, but was kind of cool in a hoosier / mullet sorta way...

Never saw the brake lights under the car but there were a lot of blue dots installed in the middle of the brake/taillights back in the day.

Getting back to air shocks I'm trying to think which reason came first for air shocks in the first place? Was it for load leveling for say pulling a trailer like an Air Stream, etc., or packing up tjhe family daily driver to head out for vacation or visit family? Or was it to jack up the rear of a car to put bigger tires on it.............I'm thinking it was the former and not the later back in the day. There were several other things marketed to help with load leveling for more daily driver/hauling vehicles that found there way onto muscle cars for changing the rear stance too. When you think of the market for load leveling versus hot rodding back in the day I don't think that Gabrial only considered big rear tires as the reason for air shocks......just my take on it.................and yes back in 1969 or was that 1970 I had a pair of air shocks on my '69 Road Runner with H70-14 tires but never really with a lot of PSI in them, just liked the slightly higher rear stance....

blue dots, i used lots of those back when !
also did the lights on the rear, mounted on the rear of the slapper bars. Lakewood's of course, when using Gabriel Hi-Jackers.
and speaking of high jackers, i just came into a set from a dart. don't know if they are any good, but i'll test them one of these days.

And the Hi-Jackers are still made! One of my reps reps Gabriel.