I agree with Ebuntu about professional help. If you’ve tried all kind of stuff that you could do on your own and you still can’t make it all happen, pay someone to do the job for you. This would be much easier and faster. You will even save some cash, instead of spending half a year on this. Just my opinion.
If you’re open to paying for this, use this service: http://www.shopping-cart-migration.com/shopping-cart-migration-options/223-magento-to-magento-migration. It will automatically move your store data from old Magento installation to the new, upgraded one.
Let me know if this helps.