Keith;

...the distributor shaft key not being seated in the driveslot of the oil-pump was the first thing I though of also...I'd just turn over engine with a wrench on the crank pulley bolt, while applying slight downward pressure on that shaft...eventually, it will drop right in for you (and a test fitting of the distrib will verify this quickly)...don't forget, if distributor drive-slot doesn't line up with the typical angle as shown...

...then you will need to turn and lift the dist drive shaft until it disengages from the cam, move it in the desired direction until you do get it...and you will need to assure that it engages the oil pump drive slot using the procedure again until you get the desired alignment...once you have engagement AND alignment, install distrib, and you're good to move on...

Cheers!