An ignition coil is an ignition coil, so the number of cylinders doesn't matter, 4, 6, 8, 10 would all use the same coil and produce "enough" spark
You could have a "bad" coil, you can't really test them, well you can test if they are "real bad" but can NOT test if they are good
So if you think its a spark issue then swap coils
In an 8cyl engine the Coil sparks 4 times per 1 revolution of the crank
So at 800RPMs the coil is sparking 3,200 times PER MINUTE
At 3,000rpm the coil is sparking 12,000 times per minute, that's 200 TIMES A SECOND
A failing coil can have a "delayed" recovery, causing misfires at higher RPMs
Coil needs time to "recharge" between sparks, doesn't need much but needs some
So its certainly possible for a failing coil to cause your issue