Best 273 and 318 builds (NO 360's please)

This might be a stupid question, but here it goes, been following this thread and something just doesn't seem rite to me and that is this. I have a 318 my brother-inlaw had in an Ply-Arrow he built back in the 80's back then he bought a set of 340 heads with a tri-angle valve job done on them and found that it didn't help at all actually hurt the engine, and have been told this ever since I got the motor, no it not in my car yet I can only wish for that rite now. So how can you guy's be talking about putting 360 heads on a 318 when 340 heads aren't a good idea, is it because you guy's have the head cut down? per say. I don't understand and my head hurts and feels like it's going to explode LOL.
Brad