Don't sweat the small stuff.
Set your top slide angle by mounting a MT2 adaptor etc between centres (reverse centre the one end) and use a dial indicator on the toolpost to match the angle.
Bore the taper as close as you can with the largest boring bar that will fit in there. Take fine cuts toward the end of the process. Use a very sharp, pointed HSS tool bit to minimize chatter.
For the last few thou, use your MT2 reamer with guidance from the tailstock centre. Turn the lathe chuck by hand or crank handle and proceed gently gently. It will follow the taper and go straight. You are only cutting a couple of thou to finish off with.
If it were to end up not quite right (unlikely), big deal. The only time it's critical is when turning between centres, and it's customary to use a soft centre and turn it true in position when doing this anyhow.
Not sure what your lathe is but I have found that with gap bed lathes such as Myford, Drummond etc you can't really turn between centres using the headstock centre as that end of the job is too far away from the carriage without running it off the end of the bed ways. So I always mount a soft centre in the three jaw chuck, turn it true and engage the drive dog with a jaw of the chuck.
Edited By Hopper on 16/11/2017 23:37:43