Focal Reduction for SBig ST7XME

I'm looking for advice on what would be a good focal reducer to use with this combination: TMB 100 f8 CNC + SBIG ST7XME + CFW8 +AO8? I see that there is a Borg model 7887?, an Astro-physics model 27TVPH, and a Televue RFL-4087 that might be appropriate. I had thought that the TMB designed WO flattener for the FLT 100 etc. might have been ideal but the owner of one has said its not compatible. I'm sure that there are probably other options too. APM make specific flatteners for the TMB OTAs but they are not reducers and are very expensive to buy new so that's not an option for me. The Baader T2 system also seems to flatten but not reduce focal length.

Any guidance including on how to interface reducers of different diameters to the TMB's 3" focuser would be greatly appreciated.

Thanks

Peter