Mystery Lift Project Gone Awry

Ok, so please try not to laugh at my incompetence here. Anyway, I have a mystery lift (was advertised as 3.5"). With it, someone went through the trouble of replacing the upper and lower control arms, track bar, installing Bilstein 5100's, etc.

Now for the problem: My rear leafs were sagging. I ordered a RE extreme duty 3.5" leaf and it turned out to be way too tall for my struts. I also replaced the shackles with OEM's without measuring how tall the lifted ones were (ridiculously dumb mistake).

Ok, so... how would you get a project like this back on track, just replace the springs and struts with another 3-3.5" set? Is there any risk associated with doing so, given all the other aftermarket parts?

Thanks in advance for the help!

...also worth noting that they're too high because I'm trying to avoid a SYE.

The year will help.

If you off-road, it pays to use a longer shackle and less spring. This allows the room for the spring to flex. A large arch spring and a short shackle will limit your travel.
Also more spring travel gives you a better ride, and less spring fatigue.

The longer wheelbase tends to keep you out of SYE territory until about 5" of lift (as far as I have taken a stock driveshaft).
'85 though '96 models use an internal rear yoke. Longer yokes are available.
The '96 1/2 and up models have an external yoke which lends itself well to installing a fixed yoke. However, if you keep it greased, they tend to do OK. The trick is to make sure the driveshaft alignment is good. The angles for a NON-SYE should be equal and opposite and less than 3deg.

I assume by struts, you mean shocks. Once you get the springs/shackles figured out, put the frame on stands and droop the rear without shocks attached. The shocks should be atleast as long as your down travel.

Your intended use/long term plans would be worth sharing before folks give you advice which way to go. For instance, is this a daily driver? A trail rig? An expedition rig? What kind of weight do you intend to haul?

Those sorts of things make a difference.