I am contemplating an upgrade on my 89 Paramount. Sram's Etap looked like the ideal way to add electronic shifting without all the wires, zip ties, boxes, etc., required with Di2. Unfortunately I cannot install Etap unless I spread the rear dropouts from 126mm to 130mm. Has anyone done this? What does this entail? Will it adversely alter the handling, integrity, durability, esthetics, paint, etc.? I'm assuming this should be done by a professional. Thanks.