I want to take apart my heads but only have a cheap craftsman compressor that was a bear to use to disassemble some eddy heads. My heads have 600lb springs so I doubt its up to the task.

I'm not going to use it too often so I'd rather not spend alot. I was also thinking about making something. I've got a full machine shop at my disposal and welding equip too.

sounds like your gonna be building your own.
You have access to the tools to do so,
anything else would be throwing money away.
Use you craftsman as a guide and just beef it up. The old school way to do things is to do them your self, when ever possible.

I've got a Lisle tools on the car type. Uses a flip lever/cam to compress the spring.

I wouldnt recommend it to any one.

Snap on makes a nice off the car type, it comes around and hold the valve up, and has a threaded shaft to compress the spring. Used one in high school, really nice.