you should verify that you are getting LP to the mixer
it sounds like its just not getting enough fuel

you can pull the inlet line off the mixer and turn on the key to open the lockoff valve and then apply vacum to the filter assy to open the LP flow and LP vapor should come rushing out of the hose at the mixer. If you get a decent rush of vapor then you can troubleshoot it from there. Check the mixer diaphram and make sure it is intact, no holes or tears. Chamber is clean, etc etc.

Just because the lockoff is clicking doesn't mean enough fuel if any is getting through it. I have seen those go bad and keep a truck from running even though it could be heard clicking.

As long as you have air, fuel and spark the engine should run unless you have a timing belt issue or something like that.
Verify the timing is ok by putting engine on TDC and checking distributor rotor making sure it's pointing at #1 cylinder wire on the cap.(if it has this ignition system on it).

Or you can just do it the old fashioned way and pull a plug, leave it connected and turn the engine over and see if its got spark ;o)

And i'd be careful using ether (starting fluid) that stuff is evil and doesn't take much at all to flood the fuel system. When bb says a small squirt, he means a very small squirt. IF i ever use that stuff at all i generally just squirt a quick burst into the air cleaner (with air filter intact) It is usually enough to see if the engine is going to run or not. Brake cleaner works as a starting agent too and is not quite as reactive as ether is ;o).