A revolting development, made all the worse by the fact that it was like this when I bought it and didn't know it.
It was making a chugging/puffing noise when I first looked at it, but it seemed to run fine, and not being familiar with these cars, I dismissed the noise and made the buy.
Well...it seems I've been running on 3 cylinders for quite some time!
I've had some intermittent driveablity issues recently, so today, I dove in to replace the plugs and wires. (keep in mind I've done plug replacement work for decades on my cars, so I kinda know what I'm doing)
Starting with #1, I immediately noticed when pulling the old plug that something didn't feel right. It came out partially, then wobbled around and wouldn't come out any further.
After messing with it for some time, I finally got the old #1 plug out and notice the electrode was gone, and looked like it had been missing for a while!
Perfect. I stuck a narrow magnet down into the cylinder to see if I could retrieve any pieces of metal, and found none.
The other three plugs came out as normal, and the new plugs went in fine in cylinders 2,3, and 4.
The new #1 plug did the same old song and dance. It threaded in fine part-way, then wobbled and slopped around. I couldn't get it to seat very well after messing with it for quite some time.
I got #1 plug as tight as I could, and put the engine back together, figuring I'd try my luck and see how she does.
She fired right up, but the chugging and puffing from #1 was very apparent, as I had not re-installed the "modesty" cover.
I could see the rubber boot blowing with the compression of the #1 cylinder, so I know I'm getting all kinds of blow-by around the loose spark plug.
I am not a happy man!
So....
What are my options?
-replace the head
-remove the head and have the #1 cylinder threads re-tapped
-replace the engine
Any others?
Can the threads be re-tapped with the head still on the engine? This would be a best-case scenario, I imagine...
I'm buggin'
big-time! 
Thanks in advance for your help and advice.