I was in axminster tools today the shop is only 2 mins down the road from me.
i worked this out ages ago im sure i posted it up. the axminster reamer is very very slightly off but i worked it out to be about 0.15mm out at the bottom of the taper over the thickness of the sierra hub that your reaming. rather than it being a pure 100% fit it was about 87% will see if i can find the cad drawing i did. was on my old laptop but i think i still have it.
either way there is more than enough material in contact. there is no chance it is ever going to wobble around in a thousand years.
don't forget if your reaming it out by hand you will never get a 100% perfect taper even with the perfect reamer.