Yes make sure there is no women or kids around when you begin install. The cussing will get really bad! LOL
If you know someone with a lift you will be a world ahead. I have never installed Hooker, Headman, headers on a A-body. I have however installed TTI headers so it shouldn't be all that different. Motor mounts should be loose so the engine can be raised. I removed the nut in the center of the mount on each side. For instance if you are going to do the driver side first, disconnect the battery, remove motor mount nut, jack the engine up on that side with a jack and wooden block, locate the block so it is on the oil pan rail, take another wooden block and put in between the engine mount and frame, that will give you more clearance. Remove the starter, you did get a mini starter didnt you?
I slide the headers in from the bottom up which made it easier for me so thats why I suggest a lift.