Damaged engine from over heating?, Need advice Options

[Flyboy284]

Ok here's the story.
She was driving 70 down the highway and the radiator breaks, makes lots of noise and the car dies. The car will not start. It has spark, its getting fuel, timing is 10 degrees advanced. I did a compression check and found the problem. The compression is (30 / 4 / 4 / 30 PSI) cyl 1-4. My question is could anything else other than a warped cyl head cause no compression. My mechanic says it is very unlikely to have all the cylinders lose compression from a warped cyl head. The car has 130k and drove beautifully a few days ago.
If the cyl head is bad should i have it machined or buy a rebuilt engine. (trying to save money)
Any suggestions?

Thanks

[Flyboy284]

Yes, the crank pulley turns easily without the spark plugs in. I did remove the valve cover and aligned the engine TDC and the belt looks like it is were it should be. (TDC indicator on crank pulley around 10 degrees).
Before the car broke down the timing was closer to 15 when running than 10
But if it slipped a notch the timing changes by a lot more than 5 degrees
The timing belt was replaced about a year ago after it was destroyed from the tensioner pulley seizing. (in case it makes a difference)
Thanks for the fast replys