LGB flanges are generally 3mm.
I have converted a Stainz to 32mm on Peco code 250 rails. *edit - I mean code 200 *
It definitely bumped along the chairs, as does other converted stock.
You will need to reduce the flange depth by about 0.5mm
Also, a problem may occur with flange root thickness, making the wheels tight to gauge using std btb setting.
This is if you're using 32mm gauge.
If your code (250) 200 is to 45 gauge, then there may not a gauge/BTB problem, just the flange depth.
Reducing the flanges is best done in a lathe, but I have done a few using a lecky drill in a vice, and hand-held file.