[dsraven]

sorry, I'm kinda on the same page as mr48. it is a customer who brought you something irregular. he will either have to pay your shop rate for you to spend hrs researching an outcome, or he will pay to have it done right the second time around (now). better to do the second option because the hrs you spend are hrs he won't want to pay in the end and you will feel like you are overcharging him, so you will reduce costs to save your reputation and you will lose money in the end. the hrs marked down or simply lost are also shop time that can be charged to someone who is waiting for your services.
grab a set of 6 stud axles that fit and slip them in, new brgs and seals, axle fluid etc. swap the brakes out, try to find the correct offset wheels for 6 lug, swap tires onto the wheels etc etc etc
OR
research for hrs, swap some (likely) soon obsolete or hard to source brake components onto the front. or have a custom built hub and rotor set made up and hope it all works together and there are no come backs or liabilities for your shop should something go awry.
either way is money, just not as much in your pocket at the end of the day. it is a business after all, right? you said customer, right? we gotta do what we can for the customer but they need to realize it costs money for someone to do the legwork for it all. different story if he had come to you asking you to install this hub and that caliper set and those rotors and those pads etc.

maybe better to ask him what he wants in the end and see what he has for power and vehicle weight that needs to be stopped. price out a nice set up that will work together, he will be happy with and has readily available parts. leave it with him to decide which way he wants to go.

just my thoughts. he will drive around on the same roads as our families though