Shane-
ChevyAsylum/Ray is correct as most headers will fit the 305/350 interchangeably. There are a couple of different set-up modes, either the earlier "ram's head" or "rear dump". Look in your truck and examine the path the exhaust will take past the steering components on the drivers' side to try and figure out what will work in your truck with the new engine. When setting up, I used an scrap block to test fit where the headers would go. in you C-series truck, there should be lots of room. BTW, the motor mounts from the Nova should work too.
You should be able to find GM headers to both types in the nearby scrap yards if cost is a factor. You would save shipping compared to ebay. Did the Nova have some?
