27.5 + front conversion, keep 29 rear, rigid geared MTB

[Erik_A]

I have a fully rigid, geared steel MTB (Singular Swift). Would it help to switch to a 27.5 + front only conversion, but keep 29 rear (due to clearances)? My goal would be to get a bit more "pneumatic suspension' from the 27.5 WTB scrapper rims and 27.5 x 2.8 WTB Trailblazer tire. If needed I have another steel fork that is 15mm longer that I could use to keep the BB height about the same (my bike also has an EBB).

What is your experience and/ or advice?