Ok, so a few months back the 4d55 I swapped into my truck seemed to blow a head gasket. I slowly got parts and went to fixing it between school and work on the weekends, and finally got it all back together about a week ago.

For some reason I cannot get the thing to run for the life of me. It turns over, seems like it wants to catch, but never does. I have checked everything I know to.
-Ran the fuel pump for a few minutes and purged the lines to make sure there was no air in them.
-Fuel is getting to the injector pump at the very least. I can hear the fuel cut solenoid in the injector pump cycle. --Tested glow plugs and swapped them for a used set I had laying around - they seem to be working.
-Checked the timing to make sure everything was right several times.
-Checked valve clearances - I only have clearance specs for a hot engine, so i figured I would add about two thousandths of an inch extra on the cold measurement - I think they are set at .013 where the hot spec is .011.

Not really sure what else to do here, and I really want to get my baby back on the road. Any advice or tips would be very greatly appreciated. Thanks guys.

Could it be the compression?

Compression test time, check the timing again if your already havn't make sure all the marks line up.

This shouldn't stop it from starting, but your valve clearances should actually get smaller with a cold engine. 0.010 mm instead of 0.025 mm I think.........

When I did my engine, I could actually feel the valves get tighter as it cooled.