Blake;
I have run into the very same problem just about every time I've tried to install a distributor. I have a "dummy" shaft I use to prime the
oil pump and all I do is take the shaft and turn the
oil pump shaft a little and the distributor drops in just nicely....
If after trying this and the distributor still will not drop in,check and recheck everything, you could have a "bad" distibutor,it is always possible....
David