I suggest you to first recalculate all keys with papuas,to get the hash and skey then convert the fullflash into swup with codes you will get and with bootcore and reflash it with that swup,then if you want you can reflash it again with higher version,if phone is slow with this one.Also in case phone beeps again,do just recalculate all keys in flash and bootcore.
Here is link with fullflash :
http://rapidshare.com/files/95362831/SL75_fullflash.rar.html