Every bike is custom. If you get a "off the shelf" or hand made bike it is stil customized to you. If you bike frame fits you then it is just a matter of stem length choice, saddle height and bar width and rotation to get your personal fit. These options need to be done to a "custom" bike as well. This isn't brain surgury, measure the distance behind the bottom bracket and set your "stock" bike to that with either a setback post or just moking the saddle. Measure the reach and determine your stem length.

These steps a bike shop can help you with and make it easier. If you are sending your measurement into a company like Seven for a custom you could make an error.