Tapered are OK toothpicks are not. The toothpicks that people refer to are the little fellows designed for whirly twirly XMA exhibitions, ¾” in the middle down to ½” at best and qualify as little more than toys.
I have tapered bo that are 1 1/8” in the middle and taper to ¾”. One that I use for kumibo against sai and although it looks like it’s been chewed on by a dog and you need to wear gloves to handle it, it is a sturdy weapon. Another one I use regularly in kumibo against tonfa and bo, no worries. Tapered are fine as long as they are stout.
Straight bo I have 5 ranging is size from 7/8” to 1 ¼”. All the bo in my collection are 6’ which are a fair match for my height and they have one other thing in common they are hardwood of either red oak or maple regularly sanded and oiled. Both wood types are quite heavy and close grained.
Grain and weight are important factors in how well the bo is going to hold up in kumibo and how much shock your hands take on impact with other objects. Tight close-grained hardwoods will not dent and splinter as readily. And the more your bo weighs the less the felt recoil on impact plus the more energy you can deliver to your target. So although the wax wood bo I’ve seen are close grained they were also on the light side.
Go with red oak either tapered or straight. But I would try for a 6’ + for your height. Shureido offers a very good product.
Patience my ass I’m going to kill something