Alright I'm out of ideas on this one and about to just throw in the towel and sell as is unless someones got a brighter idea.
Would like to get it going to sell running at the thing is really close to being fully rebuilt mechanically.
On a 2003 5.4 F-250 Brand new engine from S&J fully refurbished with a port and polish on it.

Brand new engine, new high torque transmission converter. Everything connected except coils yet.
Trying to turn the engine over in a couple series of 10 seconds to prime the oil up and tranny fluid through converter before firing.

New starter
https://www.rockauto.com/en/moreinfo...&pt=4152&jsn=1

Truck starter WONT TURN OVER, ive gotten like a split second of it cranking and then nothing.
Brand new costco battery in it. I've tested the battery with a battery tester. Cables get hot when trying to start so I upgraded them to brand new 2 gauge wiring.
Still get hot when attempting to start.
Battery is at 12.6 volts and tried boosting it with a starter to 13.2 with the same results.

New battery cables to starter
https://www.rockauto.com/en/moreinfo...&pt=2500&jsn=1

Starter was removed and tested at Orelly's and the pinion gear did spin and pop out.

So I then got new terminals to the battery.

SAME results.
Being a brand new higher compression motor do I need a higher amp starter? Wouldn't a factory rated starter work?
I'm literally at a wall at this point and not sure weather to just sell as is and use my work truck.

Thanks in advance for anything!

EDIT- Forgot to add, yes I can crank the engine over by hand clockwise when looking at the truck from the front.

 

Check your ground connections. If the cables are getting hot I hope your bearing clearances aren’t too tight.

— Dave

 

It really depends on how much compression you bumped it to, but as Djosbun stated it could be bad grounds or your bearing clearance on the crank is too tight.. The 1st thing I would do is remove the plugs and try cranking it with no compression, if it cranks fine then you can probably look at the starter or wiring, if it doesn't crank then your crank bearings are too tight maybe seized.

 

Can you spin the engine with a breaker bar on the crankshaft?

Will the starter spin and the bending gear extend when it isn’t bolted to the engine.

 

Update, sorry to ignore everyone, life's been very busy lately.

For anyone that hits this post in the future. Here is/was my solution.
The starter is grounded out directly into the block. You DO not run a ground wire off the negative side of the starter, your ground from the battery goes directly
into the bell housing of the engine itself. Essentially I was just creating a giant short from the battery through the starter by trying to run a ground off the negative side of the starter back to the battery.

Its been so long since I removed it I can't remember if that's how the factory starter was or not as this is a new one.
Runs really nicely now.
Heres a link.
Slightly modified 5.4 with a port and polish, cold air intake, and a cat delete.
https://youtube.com/shorts/LyLI09IxugI?feature=shareb
Looking to for info suggestions & advice on a nice tune for it.