Yay! Old stuff!
Well... two options:I don't think there is a good way to blend them and I will NOT modify the Modellista kit.
With enough time/money/work it could be done. I just don't know if I want to mess with it at this point.
1. You buy the brand new authentic Wald side skirts I have and you love your life even more so than you already do
2. You sell your wald flares to me and then I do the whole loving my life thing like no.1 only reversed roles