Oil pump was going out? As in you've had weak oil pressure? If this has been the case for any length of time, pretty much everything in the engine is going to have accelerated wear because of it.
Unless it did run really good before, I'd suggest starting over with another engine. The 318's are pretty easy to find, the 360's are harder. At least in my nick of the woods.
If possible, put a compression tester on whatever engine you look at. If the seller won't let you, walk away. No sense in spending money on an engine with a weak cylinder that's going to give you power issues and ultimately have to be pulled down the line.
Honestly though, if you hit another truck hard enough so snap the crank, the bodywork is probably going to cost you much more than the engine swap itself. Did the air bags blow? You might want to consider just buying another truck, unless you really like this one.
