agent_orange I'm in exactly the same predicament with the lack of upgraded F25 tension arm bushes.
It looks like E39 540i, E39 M5, E83 X3 and E53 X5 ones have a 66mm outer diameter and 14mm inner which makes it very tempting to try and squeeze a monoball kit designed for them in. NVH is no concern to me (other than squeaking which would drive me crazy. I hate poly bushes with sliding inner tubes). I just need to minimise the forward and backward movement of the front wheels because I put much bigger tyres on for off-roading and they scrub like crazy.
The other one I'm tempted to try is a 200 series LandCruiser rear trailing arm bush. It's listed as 65mm OD. Some sites sat 65.5mm so should be perfect. Also 14mm ID.
https://febest.de/en/details/bushing...ng_arm-tab_480
Did your Powerflex bushes and sleeves come out without damage? I'm a little tempted to try them, at least temporarily, if you still have them and would be willing to sell them cheap? I'm in Hobart.