You will find that everyone has done the V8 thing differently, so to say. Ford , Chevy, Mopar will have different ways to install. Get your mounts installed and see if you need to enlarge the area in the truck for the bellhousing and room in front for radiator, etc. I have not heard too much about changing steering and oil pan might make the cross member be moved. As for manifolds, there is a lot of room under the hood of these trucks. Shouldn't be much a problem just don't drag them. There will be fabricating and it will probably have to be decided as you go. Haven't seen a direct bolt in yet.
There should be someone that can help you out a little soon. The one I know of has a ford engine, so I'm not sure if it will help when your doing a 318. Keep banging.