Ha! Leedybdp is gonna love this one! :-)
That "knuckle scratch" on the batter head is caused by using a 1970s (or later) SK on an earlier bass drum. In ABOUT 1973 (as close as I can determine), Ludwig - for some reason- increased the width of the wooden hoops by slightly more than 1/4".
This set the SK further back from the batter head, admittedly a self-induced problem. Their solution was to shorten the "spacer" at the bottom of each "goal post," so that the SK would sit closer to the batter head.
So there are two types of SKs - those with the long tab (long spacer) and those with the short tab. Putting a short-tab SK on a pre-1973 bass drum hoop will cause the knuckle to rub on the batter head. So you have to swap something out - the SK or the hoop, OR just position the SK so that it is slightly to the rear of being fully pressed forward onto the hoop.
But still, I love the Speed Kings! I believe! ! ! ! ! Ha!
Regards, MB