I have three types of taper pin reamers.
1. Hand, with square ends for a tap wrench and straight flutes, stored in an oak block that I made.
2. Machine, with round shanks and left hand spiral, right hand cutting flutes, stored in a steel drill stand and a smaller set in a cool aluminum stand that I bought somewhere.
3. Machine self-drilling reamers made by Capital in England stored in a black plastic drill stand. Note that these have a right hand spiral and chip breakers, and the ends are ground like a drill bit.
All of them have the standard US pin size on the shank, from around 7/0 to 10.
I have a good supply of pins, but can't recall the last time I used one. I started using them around 1964 and occasionally for another 25 years or so. They are just the thing for some jobs, and I find them in some of my old equipment.
By the way, I do have a bunch of tapered end mills, bought when the local GE die shop auctioned off. They are used for making dies with specific draft angles on the walls. I tried to use one for reaming a tapered hole once and it made a mess, leaving chatter marks in the hole. All of my tapered end mills are marked with the side angle in degrees.
Larry