xl97:
I have what I believe to be a FLASHED chip with Optiboot on it. Since it 'auto detects' the chip signature.. and there is no 8Mhz version.. (and you cant choose anyways.. Optiloader just 'goes'..and runs when a chip is detected)... this chip is set-up to use 16Mhz.which Im assuming will NOT work in the final/target board that is set up with an 8MHz external resonator..
It will work. Trust me. The bootloader will run at half the normal speed, but that's just fine. Once the bootloader has finished running it passes control to your sketch, which will run at the speed you expect just the same as on any other 8MHz board.
You could recompile Optiboot for an 8MHz processor. You will find (I've tried it) that at 8MHz the "normal" baud rate of 115200 is unreliable, so you'll need to slow it down to 57600. But now the 8MHz version of Optiboot is (aside from some very minor cosmetic issues) exactly the same as the 16MHz version. The instructions to communicate at 115200 baud, if carried out at half speed, correspond precisely to 57600 baud.
The only problem you have is that there is no standard Arduino which uses Optiboot at 8MHz, and that means that you cannot use one of the existing definitions in boards.txt. But that's very easily overcome, as described above. If you really really do not want to alter boards.txt, then you'll need to start over (although the 16MHz jig will still be ok).