I've seen a number of reman injectors with the solenoid backwards, I think it has something to do with the test stands that some rebuilders use. It's no problem to remove and rotate the solenoid. If the solenoid was 180° out, just rotate it. If it was rotated only 90°, you may need to rotate the armature under the solenoid as well.
Next, when you had the injector out, did you purge the oil and fuel out of the cylinder? The easiest way is to remove the glow plug after the new injector is installed, replace the valve cover with a couple bolts and crank the engine (valve cover harnesses disconnected) which will blow most of the fuel and oil out into the lifter valey. You can then reinstall the glowplug and reconnect the harnesses and fire it up.
FWIW, some people prefer to use a vacuum pump or other method to purge the cylinder. Whatever method you use, you do need to do it.
Now, when you go to start the truck, it will likely take a lot of cranking. The high pressure oil rail on that side of the engine is empty and will need to refill before there will be enough pressure to start the truck. Some people will put oil into the rail through one of the plugs to aid this process. When it does start, it will likely run like crap for a while. It will smoke and sputter for a bit, and then it just won't feel smooth and "normal" for sometimes over 50 miles until all of the air is purged from the high pressure oil system.
I hope that's helpful...