Kevin,
One of the best ways to clean the engine is to never spray anything directly on it. The LT5 engine paint is sensitive and will stain if you give it a dirty look. Over time, oil buildup will stain the engine, and especially coolant. When you have the coolant system flushed, always take extra care not to splash any coolant on the painted surfaces of the engine, or they will permanently stain and quickly!
I start out by vacuuming the engine compartment. Go to your local Target or KMart and pickup a vacuum hose kit that comes with all the nifty little attachments. These work great for getting into hard to reach areas as well as around the frame rails and suspension components.
For a dirty engine (dust, road grime, etc.,), I spray some Simple Green on a cloth towel and wipe down the engine and related components. THEN, I take another towel that is damp with water and wipe down the motor again making sure that I get all the spots that I used Simple Green on. Simple Green will permanently stain the engine if you leave it on and the engine gets hot.
For the rubber hoses and related rubber components, I use Meguiars Vinyl and Rubber Cleaner and Conditioner. It gives the rubber components a nice but not over-greasy appearance and helps to clean and nourish the rubber.
Now, some folks will say that you should never do this next step and I will leave it up to you. I am speaking from experience with my own motor here. I have used Meguiars #7 Showcar Glaze and Meguiars #27 Yellow Car Wax (I believe it's #27...) on the painted surfaces of the engine (valve covers, plenum, etc.) I start with a coat of Glaze, wipe that off and then put a coat of the Yellow Wax.
Once the engine is cleaned, for maintenance, I use Meguiars Quick Detailer and that's what I use to wipe down the motor and keep it clean from dust and dirt.
Basically, I'm hoping to release a technical article with pictures of my engine shortly. You can get an idea of how mine looks then, or stop by the Members' Gallery linked above (under Reviews tab), and go into the Member Galleries and look for mine. I have a picture of my engine posted there. Hope this helps.