#6 not firing!

Hey guys I am in need of a little input. I just picked up an 81 truck with a /6 and the #6 cylinder is "missing". I have spark all the way to the plug. I pulled the plugs and swapped in new ones and thats when I noticed that #6 was fouled black. All the rest are nice and clean white. I them pulled the plug wire off to see if it changed anything and of course it didnt. So Im sure its that cyl. I havent done a compression test to check anything further but thats my next step.

Any ideas as to what it can be?
I am thinking
1. burnt valve
2. stuck/bent valve
3.flat cam
4. collapsed lifter
5. Bad rings.

If I come up with a good compression test, then what? Guess itll be valve train at that point yeah?