Case 580C, 207D, backfire rough running

I'm kinda new to the forum hope I'm in the right place. I just purchased and installed a "rebuilt" engine in my backhoe it's a 207D in a 79 model Case 580C. I installed the engine and it runs a little rough and throws a backfire here and there with plenty of white fuel smoke. Contacted the place I bought it from and they sent me a set of new injectors Installed them and no difference. Then they sent me my old injector pump back installed it and still no difference. I'm fairly certain I have it in time according to the manual. When I swapped pumps I lined the flywheel up at 0.0, the #1 valves were both closed and the timing marks on the old pump were lined up. I have not checked the timing gears themselves but am about to do so just to give me piece of mind. I did the old rubber glove trick on the radiator and the oil filler neck and no blowby that I could see. No coolant in the oil or oil in the coolant either. Anyone have any insight or ideas as to what I've got going on here or where to look?

Have you checked your valve lash?

Have not checked the valve lash. How do I go about checking it on one of these?

Just got off the phone with a farm equipment technician and he mentioned the specs for the 207D's that he's worked on were timed around 8-10 degrees advanced. I wonder now if mine should be advanced or TDC?

What about the 2 lines in the side window on the inj pump.??
If the pump drive shaft was left in the engine, did u line up the dot on the end of the dr shaft to the dot inside the pump.??

Yes, turned the engine till I was TDC on the flywheel, both valves on no1 were closed, and the pump lines were lined up. Removed the old pump and lined up the other pump when I installed it.

Did you turn the crankshaft clockwise slowly to the timing marks ?
If you go past them do not turn the crankshaft backwards (counterclockwise).
The slack in the timing gears have a significant effect in the pump timing.

Here are the timing specs. Notice you need to determine which injection pump you have will depend on where to set it.