Rough-idling 360, can't figure it out!

So fuel pressure is a part I haven't looked into yet but obviously should have. It has a new Carter mechanical pump but it pulls from what used to be the auxiliary tank under the bed so it might not be flowing what it should especially at idle; I have no idea the condition of the pickup or "sock". I need to go buy a fuel pressure gauge but first I'll try spraying carb cleaner down the primaries when it's idling rough first. Regardless I'm also going to relocate the filter.

@Dartswinger70 I did a compression test with the old heads, one cylinder was down a bit but it had a burned/sunken exhaust valve which is now fixed. I do have a Chilton manual for the truck I'll check over the tune-up section in there.