Tommy;

I'd do this after vehicle was recently driven (an engine compartment with a block radiating heat dries faster). Spray degreaser onto specially greasy areas or where lots of dirt has collected in weeping oil, and let it soak for a while...you could even do this days ahead...don't bother covering carbs, their linkages could likely stand some cleaning also (relube after!), just don't blast power-washer or steam-cleaner at air filters...they're only paper, or FuseBlock (it doesn't need extra water in it to promote corrosion), or hydraulic reservoirs for obvious reasons. You don't even have to cover distrib...a little water wont hurt it either...have you ever seen under the hood after a highway drive in the rain?...EVERYTHING IS SOAKED! There is a chance engine might be difficult to start or run rough afterwards, but don't stress, just wipe down Ignition wires and maybe under Dist Cap and that should allow it to run...it should be fine after a short drive and drying out a bit...then the polishing can start, but remember deoiled metal will rust, so paint, wax or protect with clear spray!

Cheers