when i built this thing i tried as hard as i could to find a 55 but i only could find ones where i had to wait about a 5 mounths to get so i was wondering if i could oc my 53 and make it a 55
Really depends on the luck and stepping of your chip if you want to get it to 2.8Ghz.
You should be able to get it to 2.6Ghz on the stock cooler easy with your chip witch will be on par with an real FX55.
As for flashing it there is no way to do it.