There are 4 bolts that hold the k-member in place. I am referring to the front 2. And no, 4.25 is not the standard BBP backspace. OEM Chrysler wheels are always centered. A 15x7 rim would have 3.50" backspace. Add 3/16" for the lip. The original OEM Chyrsler Cordoba steel 15x7 rims that I have don't fit. The backspacing is wrong.
Ok, let's correct a whole bunch of stuff. A "centered" 15x7 would have 4" of backspace, not 3.5". A 15x7" rim is 8" wide outside lip to outside lip (7" is the width where the tire seats), and backspace is measured outside lip to wheel mounting surface. So a 0 offset 15x7 has a 4" backspace. You can check this on any wheel calculator.
OE Chrysler wheels weren't "always" anything. OE SBP wheels were typically 0 offset. OE BBP wheels on the other hand were often +6 offset. Which makes a 15x7 a 4.25" backspace. You can see that with these very much OE police rims. You can see the 4.25" backspace measurement, as well as the original stamping including the part number, size and manufacturing date. These are from '84, but all of the steel police wheels were the same, 15x7, 4.25" backspace. There was the same design in a 15x8 but those were truck wheels and had a 4.5" backspace. I didn't say all BBP 15x7's had a 4.25" backspace, but it
is a factory spec, as I said.
As for your height measurement, that's kinda what I thought. That measurement means your frame rails are sitting on your LCA bumpstops though. I don't drive the lowest car around, but it sits pretty low. On my car the measurement to the front K frame bolt is ~12". More importantly, my LCA to frame measurement is only about 1". Now, a bunch of stuff goes into that measurement, like tire height. Except your tires are 26" tall and mine are 25.7", so your tires are actually raising that number. I also have tubular LCA's, which increases my LCA to frame number and allows for more travel.
So, bottom line is if you're not running 2" drop spindles to get 11" at the front K frame bolt you pretty much have to be completely bottomed out on your LCA's. Now I suppose it's possible you're running a TON of rake, which would effect the height at that K member bolt since its forward of the spindle. But with little .88" diameter torsion bars it doesn't really matter, you won't have enough suspension travel at that height to have functional suspension with those bars.
Unless I'm somehow misunderstanding how you're taking that height measurement. Which is possible, which is why I asked for a picture. Same would go for your LCA's at this point.