I have a 67 F'bird with a 1970's? 400 engine with 6x heads. The #3 cylinder is dead. (The engine is 'missing' a little bit and there is no rpm drop when pulling this plug wire) I have verified it's getting a spark and the plug is good. Compression is 135 while the rest are 135-150. Rockers are moving up and down when cranking over. Valve lash is good. The spark plug is alot lighter color than the rest which leads me to believe it's not getting fuel. My next test is to squirt starter fluid around the intake port when running. If nothing shows (like rpm change), I will do a direct measurement on the valve lift travel using a travel indicator. I'm shooting in the dark here, I don't have a lot of engine experience, can someone please help.  

I think you are on the right track but be darn carefull with starting fliud. If you disconnect the fan you can use a propane torch, no flame ofcourse to do the same test. You might check the distributor cap and plug wire also.  

You've covered the bases pretty well, the compression sounds good and as long as both valves are opening at all, the cylinder should contribute something- if it is getting spark. Since a cap and rotor are cheap I would replace them anyway and try another spark plug and wire. Sometimes a weak spark will jump the plug when you have it out of hte cylinder and grounded, but when it is back in the hole with compression acting on it the weak spark can't jump the gap. Start with the ignition, then check for vaccum leaks as you stated and if that doesn't solve the problem, the next step would be a leakdown test. I know your compression test passed ok, but sometimes a slightly burnt valve will not show up. You need to do a leakdown to find out for sure.
Steve