just seen some coils on ebay gsxr 750 j-m slingshot 88-91
3.5 ohms primary
18 k ohms secondary
BUT MY SPEC FOR THE ABOVE BIKE ON TESTING IS PRIMARY 2.5 TO 3.8 OHMS
AND SECONDARY 30 TO 50 K OHMS

THE PRIMARY IS WITHIN SPEC BUT WHAT ABOUT THE DIFFERENCE ON THE SECONDARY WHAT DOES THIS MEAN AS ITS LOWER AND IM NOT AN ELECTRICAL GUY WILL A PAIR OF THESE NOT WORK?

They need to be physically the same size for mounting purposes. They need to offer as much power as the ones you have in, otherwise it will misfire at high revs and full throttle.
You can generalize a coils power by its impedance, but not always.