Tested and worked fine on two PSP's..
One white 2.71 TA-082 and one black 2.71 TA-082...
Cutting a long story short, I downgraded both of them to 1.5 successfully after going through the readme instructions.
I then got the 3.02 OE-A installer package for 1.5 and it copied over all the necessary files. I then ran the install from the xmb on both psps and volla we have two ta-082's on 3.02 OE-A...updated them both to OE-B...
Only thing I did was in the recovery folder I replaced the update.pbp with a 2.71 eboot to revert back to.
Thank you Dark Alex, Mathieulh and Harlyg