I ordered stock front coil springs from Summit for my 70 skylark 455 convertible. I don't want to change the height at all. I'm redoing the suspension, undercarriage thought I should change springs. Anyway there's around 1-1/2" difference in height but the new ones have a thicker coil. Don't want to put news on if it changes the height. Sorry not the greatest of pictures.
Is there a part number on the box? I installed 5536 Moogs in a 69 GS400. I achieved the stock ride height with them.. http://www.v8buick.com/index.php?threads/moog-5536-front-springs-vs-originals.385092/
The thicker coil has a higher spring rate and can support more weight.... it doesn't need to be as long. Can't say what the new ride height will be without knowing all the specs and the weight of the car at the front corners. GrenSky installed the UMI 1" lowering springs in his 350 Skylark, he thought they were on the high side. https://www.v8buick.com/index.php?threads/umi-front-lowering-springs-not.387732/#post-3415043
Based on @breakinbuick11's experience, I recently ordered a set from ESPO (https://www.springsnthings.com/). I think they custom make them. Wasn't cheap ($195 IIRC) but not nearly as expensive as Eaton (which despite your name I assume you have no relation to).
I'd feel a lot more confident ordering/installing a set from ESPO than installing UMI's, especially since I assume they're not returnable once installed. I don't get anything out of this but if you do, feel free to tell Laura I recommended them. I think she's the owner. I probably should've asked if they'd offer any discount for a group purchase & if so put it up on here. I bought 2 sets & certainly wasn't in any hurry for them.
Laura @ ESPO is pretty sharp, knows the math to spec the correct spring. I last purchased from them back in 2006, pricing was competitive with Moog, under $100/pr. Several guys on 65gs.com have purchased from them as well.
