been doing my engines for years, and i keep them super clean
i used what you already mentioned, also GUNK spray and WD40 the whole lot afterwards to stop oxydisation
for bodywork parts i use normal car cleaning methinds and polish
all black plastics i treat with rubber care, auto Glym bumper car to be exact
End up with summart like this (although iv gone a step further and polished aload of bits up)

I dont believe in steam cleans or pressure wash on engines, im sure a few on here will think otherwise but for me its a NO NO