You need the proper switch with the wiper motor, otherwise one of 3 things will happen:
1) Nothing happens
2) Something happens but is not working right
3) Something gets fried
The delay wiper system works on resistance to control the delay timing and the speeds (high and low), where as the non delay just uses simple switches to control speeds.
I just did this conversion to my Jimmy about a month ago, swapped an S-series tilt column in with delay (I wanted tilt anyway

), and used one of my J-body wiper motors, worked like a charm, just like when I did the same thing on my '84 Sunbird, swapped both the switch and teh motor and everything worked together.
BTW I am moving this to repair/troubleshooting.