If the engine has sat for 20 years it's possible that the cylinders have dried out.  I had that happen on an old 1963 Bonneville.  We cranked and cranked and even tried towing it to jump start it (automatic, you have to hit at least 40 mph, apparently, to get the engine to turn.  It was fun.) but it wouldn't start until a farmer drive by on his tractor and said "squirt some oil in the cylinders".  Fired right up.

Squirt some oil in to each cylinder to help the rings seal, to generate enough compression to get it to fire.  I'd probably do that anyway just to be sure that the cylinders have good lubrication prior to the first start in a long time.  Might save some rings and cylinder wear.  

@Zed HeadI tried the starter fluid and it didn't respond at all.  I will test the plug and squirt the oil in the cylinders. Thanks for the suggestions

If it doesn't even try to bump over on starter fluid, I would investigate the ignition system

Per @Patcon's suggestion, here is a video showing how to check the spark: 

When you add oil to the cylinders, make sure you

1. don't add too much
2. take out all of the spark plugs
3. turn the engine over by hand if you can.

Also, considering the time it sat, I hope you did drain the gas tank of the old fuel. 

 

The video suggestion would work well if all of the wires and other parts are clean and intact.  But bad wires, crusty cap, etc. might lose the spark before it jumps that big gap.  Might get sidetracked.  It's worth doing but a spark plug in the wire will give a test of the ignition module and distributor trigger.  Then the video gives a spark strength test.  Just saying...