I found the problem with the misfire in the high rpm, cheap sh*tty after market plug leads, as you all know the tops have to be taken off of the spark plugs in order for the 8v plug leads to clip onto them well I has a set of leads that require to keep these on and it meant the metal shroud didn't sit on the plug properly if you know what I mean, like it didn't push on far enough and when it was dark it could be seen arcing and when reved high when stationary they were arcing to the head very badly, big blue cracks, I put a set I had in storage on that are 20 years old and brittle/moulded into shape, and what you know it stoped doing it right away, so a nice new genuine set shall be ordered
no idea how the cam timing decided what rev band it happened at tho, who cares it's fixed
