Cleaning before a reseal?

[Soundmound]

SO I definitely need to do a reseal on the 305 that's in my rig now. However it's covered in gunk from the intake to the oil pan and I'd like to see where my pain points are.
The question is what do you all find the best method to "wash" down the engine bay? I've seen some YouTube videos and man do some folks play fast and loose with the rules! To complicate matters I live adjacent a river and would be using a catchment tray so minimal water would be preferred. Otherwise, I guess the option is to take it to a pro, but I'd rather have the satisfaction and peace of mind knowing it didn't take 3200psi to the face. Thoughts or experiences?