You'll need to upgrade your coils if you don't want ones that screw on.
Accel or dyna makes ones that work. Apparently they're a big upgrade and come highly recommended, although not because they clip on, it's because they produce a stronger more reliable spark.
I have some Accel coils I got in a parts bin that I'm going to test as soon as I get my bike back together.
1981 CB750K with 900 cams
90K KM's, rebuilt head, rebuilt carbs, upgraded valve stem seals
My wife's recipe website that I'm trying to help promote:
Strawberries for supper. Yes, I am a lucky man.