First start up engine won't turn
 

Transmission in neutral ?
Correct flywheel ?

If the transmission is in neutral you should be able to turn it over by hand unless the starter is hung up on the flywheel. Did you remember that you have to push in the clutch to turn it over with the ignition key? It wouldn't be the first time this has happened.

Yank the starter and turn by hand and go from there.

You said you tried turning it by hand. Said it turned by hand before installing the transmission.
The problem seems to be the transmission.

So it 10000% turned by hand before putting it in the car. I just removed all of the transmission clutch and flywheel and it still won't do one full turn. I'm at a loss I don't understand. I guess all I can do now is drain the oil and start breaking it down. I suppose I'll start with the push rods and rockers.

Yes and yes

That's what I thought and hoped but after pulling it all it still won't do a full turn. Only about 3/4 of a turn.

Back off the rockers and see if it turns then. Also pull the starter.

How hard was it to put the transmission in. Lots of force? Did you use the bolts to pull the transmission to the engine? I’m thinking the crank maybe jammed forward into the thrust bearing.

Was it turning over by hand with the rocker arms installed? Could be possible you missed a lifter cup when installing the PR's and now it's binding up.

Yes it was all installed when it would turn over. I'm gonna try to loosen the rocker tomorrow

Yes it was all installed when it would turn over. I'm gonna try to loosen the rocker tomorrow

No problem getting it in the engine. Did not use the bolts to pull it in. Is it possible the bolts pulled the crank to the back?

The transmission install is the problem. If it turned over with the rockers on before why are you going to mess with them?

The transmission is out now and it still won't turn 100% over.

Knew that was coming....hence the reason I asked you to pull the starter and springs. Putting the trans in just so happens to correspond when you tried turning it over. Your problems are in the engine.

Thus is an unusual LS problem!!! If it spins 360° after rockers are removed, either a bad trunnion, or valve to piston...

1000000% something dropped into an intake port.
Did you pull the intake to install it?

Engine turned 360° with the rocker arms installed and before transmission was installed but now after removing the trans it dosen't? I find it strange to all of a sudden have an internal issue which leads to other questions like was the timing cover, valve covers, windage tray and oil pan installed at the time the engine was turning over by hand? I'm pretty sure that bolting a flywheel to the crank isn't going to keep it from turning over either and if so the problem would have been with the flywheel and visible. If for some reason the thrust is the issue this should have been verified before the connecting rods went on. Just as you should be checking for side clearance after rod/piston install.