my brothers plow truck.running ruff . guy he knows has friend who had a new set of 350 heads off crate engine and after doing a compression check decided to replace heads with the 350 heads.then he calls and tells him he found out the heads had to be drilled.he didn't know what to do and is just trying to get this truck to last for 2 more months.so he ask me what i thought and i have no idea. that's is why i ask.