Why not just use the bodies and rechassis them at the same time-Parkside and Slaters etc are commercially available and the overall look will be transformed, even going so far as to fir W-irons if you so wish
You're right about S scale being addictive Phil-having spent two hours yesterday operating John Coulter's 'Llanfair' at Porthmadog show!
And he's talking me into S scale too........