From what I know a direct reverse of a stock spring does not give you the correct eye to eye measurement to keep your shackles at 45 degrees. However, it will work and has been done before obviously, but not my first choice...
Look at the tutorial loudpedal put up here probably 10 years ago. that 's what I used to do mine and it is actually pretty simple. You need a vice, hydraulic jack, chalk and the ability to make a jig or have one made for you. Truth be told I did snap the first one in two...but you'll get the hang of it. This is the basis of Hot Rodding.
You are quite correct about eye to eye center changing. A few years ago this subject was debated here. At the time, I did a drawing that easily illustrated the difference. I thought I had a photo saved, but a search just now failed to find it. Perhaps a verbal description will help visualize the change. To start with, if you had the leaf perfectly flat, there would be no difference in eye spacing, right side up or down. However, with an arch in the leaf, the geometry changes. Imagine the leaf as it sits in the car, moderate arch, with the eye on the bottom (stock configuration). Drop a string straight down to the ground and mark it. Now imagine the leaf, with the same arch, but the spring eye above the leaf. The eye will now be slightly outboard of the previous configuration. time out! I decided to do a quick sketch...... This isn’t as ‘clean’ a drawing as my original, but illustrates the change. And the change is times two because, of course, both sides are affected. Ray
Yowzer! $127 for a reversed front main leaf? I flip my own and have done so since the HAMB taught me a million years ago... I even did all four on a '57 Chevy truck I had...
i reverse my own too. however, due to the increased length, my shackles do not sit where they should. not bad i originally thought, but the car does wander a bit even though every thing is new. guess i better check toe in again because 127 is toooo much