I am attempting to raise the rear ride height of my FF MK3 about 1", and I am struggling with how to accomplish that given no more room to raise by adjusting the threaded collar on the existing rear coil-overs. The threaded adjustment collars on the Bilstein's are at the top of the allowed travel. The ride height should go up 1/2 to 1" to make room for new FF Halibrand 17" x 9.5" rims and new rubber (275/40/17). I finally have the car up and unloaded on the lift today (where it now sits), and was able measure the springs this morning. They are 10"L x 1 7/8" ID, 250# rated. "Factory Five" is still visible on the springs as is the part number #12590, which matches an invoice found in the documents passed on to me from the original owner.

I purchased this car from the original owner, who had it built for him, so I don't have the history of his efforts to address this issue. Consulted with FF via email and they advised to install longer springs (e.g., 12"L vs existing 10", making sure to match ID" and # rating). Today I spoke to tech supports at both Summit Racing and JEG's, and neither have a 12" spring with 1.875" ID (they only had 2.5" at 12" L). Attached is a picture of the rear coil-over with the car/spring fully loaded to show what I am trying to describe.

I just Googled the topic and found some old threads about spring length issues with Bilstein's but couldn't find clear posts on how to resolve. The original kit was shipped in Feb. 2005. Any guidance on where I should go next?
Rear Bilstein Coil Over Spring.JPG

Thank you.