Overheating issues with remanufactured 360

Thanks for all of the responses!

It has overheated since we put the engine in, we start it and it slowly creeps up if you leave it idleing, or drive it.

We replaced the thermostat twice i believe with 180's.
Someone was saying to just run it without it, is that recommended?

My dad and i have been working on this car for a while and hes getting frustrated because hes a Chevy guy. We always had a project car growing up we have a SS 396 Chevelle, several Novas, a factory slant 6 diesel Dart (forget the year), etc. I personally like Mopar and i bought this to be a father son project when i was 17 or 18. Ran fine with the 318 but a hose popped off the manifold and it got too hot too quick and blew, we decided to get the 360 and have been trying to find the overheating problem for a little over a year. Waiting to do body work and get it polished.

Here's some pics of the engine and cooling system