Greetings, Sebastian from STALLIONi ,
already we did similar migration from OSC to Magento
Let we discuss?
Please check our freelancer profile http://www.freelancer.com/u/graphicaa.html - that evidences our works.
We also have staff in two different time zones, so that I can get back to you promptly, no matter where you are in the world.
We will extend our service support after launch too.
We will be flexible for betterment
Thanks & Best Regards,
Sebastian