Timing pulleys and axle sizes

How do I solve this problem:

I have a servo motor with axle diameter 14 mm, which I want to couple
to a lead screw with 8 mm journals. I'd like to use a timing belt
with a reduction of about 2.5:1.

The pulleys I have found all have a bore size too small at the motor
end and/or too large at the lead screw end. Should I try to drill the
bore at the motor end to fit the motor axle?
SDP/SI (www.sdp-si.com) has timing pulley with 20 grooves, 6 mm
bore size, 20.60 mm hub size. I guess this could be drilled to 14 mm
bore size, but that would leave only 3 mm of material for the set
screws.
Also, the mating pulley at the lead screw side (50 grooves for a
reduction of 2.5:1) has a bore size of 12 mm, 4 mm more than the lead
screw! How does one solve this?

The motor has a continous/peak torque of 0.64/1.91 Nm. I do not have
easy access to a lathe.

Arvid