^ a lot of builders LOVE to make a huge deal out of how surgical you need to be when assembling...i'm not saying its pointless, but to some degree i've found it to be a 'me too' type of thing...With Nissan always thumping their chest about how GT-R engines are hand assembled inside a vacuum chamber, i guess it was inevitable...
its just i've seen what the common machine shop looks like...the place where all these parts are printed before most of us get them...and its hard to find one that is spotless...and in a lot of cases; far worse than the average home mechanics work area...
I'd say you'll be fine with plenty of time, plenty of alcohol, wd-40, nearly limitless clean rags...a fan blowing out of your garage (for dirt, as well as fumes)...and setting up a shop vac hose within a few feet of your stand...keeping the air moving around in the garage will limit most particles from settling on your assembly...for an F1 engine, that wouldn't be the best way to do it...but you're not building a $100k+ mill...just work slowly and triple check surfaces are as clean as possible, and keep stuff coated with wd-40 to prevent rust...more important than removing all traces of dirt, is to not sandwich corroded parts together...and traces of rust will form on bare iron block surfaces literally in minutes, even though it won't yet be visible...
as you move along, it gets much easier...and you quickly learn the order to do things...buff with alcohol, wipe dry, coat with wd-40, quickly assemble, move to next part, etc...don't clean things tonight, then assemble those areas the next day, for example...