<VV> Oops - need advice

[Joe Hennerfeind]

I don't want to ask this silly question, but I have never had this happen to me and need to know the best way to resolve it...I managed to break off a spark plug today in my 65 140 even though I had been soaking it for days with different products.  Where is the best reference/guide to get the remainder out?  I have a screw extractor set but have never used it before and I am unsure if it will bite into it enough to give me enough torque to try and get the remainder out (and if it will put metal shavings down into the cylinder).  I was planning on pulling the motor for a reseal anyways, so should i just wait and pull the head and take it to a machine shop?  Or maybe just find a good used one?  Is there any chance of getting it out while the motor is still in the car - I was in the middle of assessing the motor to see if it is still good (I got 120-130 lb readings with the compression tester in the rest of the cylinders and this was the last
 cylinder).
Thanks, Joe