I just did this same thing a couple of weeks ago. I swapped in MPFI running in batch mode on my 95 tahoe's PCM 7427. When I found out the pulleys were different, I just grabbed one from the junk yard. It fit right on like it should and worked.
However, I also changed the entire front of the motor to Vortec. Both accessory brackets because one of the old TBI brackets hit the Vortec intake, making it impossible to install the intake. I also had to change the power steering pump, replace the AC compressor with the newer style, and move my alternator over to the left side of the motor. It was a major PITA, but it is all done now, and works well.
I have electric fans, so I didn't mess with the belt driven fan on the vortec.
Oh yea, BTW, I also needed to replace the belt. My old one didn't fit either.