4.3 Crank Sensor

I did a 4.3 engine swap in a 96 Astro van. I used a block from a 91 Blazer and put heads and everything else from the 96 on the 91 block. Now comes my problem! I could not install the oil pan or the timing cover on the 91 block because the bolt patterns were different, so I used the timing cover and oil pan from the 91. Now engine won't start because there is no crank sensor. What can I do to get this thing done and out of my garage? Is there a quick easy fix or can the crank sensor be bypassed somehow? Any help would be greatly appreciated!