Doubtful the scaling is going to make much difference unless the seat is very centered (which is almost impossible given a 206. A bigger driver on vega blues is at a big disadvantage and 2 wheeling is the common issue. You may be able to move the seat to the left slightly to help with the problem but it’s likely you already have 50% or more distribution on the left side.
I would also try removing the seat stays.
Lowering the seat is easily the biggest change you can make to fix your problem aside from widening the rear track (which you can’t). If the seat lip is more than 8 1/4″ from the top of the axle then that needs to be your first priority to tip it back along with lowering it below the frame. As a bigger driver I have dealt with the issues for a long time.