Cool, well still handy having your dad's garage! Looks ideal from the pics. What web store? We have a section for members business on here, get a little post up and sell it!
As for a catch tank, not so much, mine is (will be) an open breather tank setup. The general view is to free up horsepower and increase engine life be removing harmful crank case pressure (and oil/fuel vapors you mention) that builds up in high horsepower NA, turbo, supercharged and nitrous setups. Pretty much what most of the nice Honda builds are doing, I'm sure you've seen.
Is that the kind of thing you mean too?
I've got my AN10 ports and my rocker cover is finally done ready to have them welded to the front and some baffle added. Then it's some more black AN10 braided lines to the passenger side recess to a custom tank with some breather filters on. Just not had the tank made up yet. Got a company in mind I spoke to at Japshow last year. A really helpful thing, but more work, is to tap an oil line from the bottom of the tank to the engine sump to act as a return line, so you're not losing the oil all the time. All my other PCV, EGR, etc systems have been removed from my setup, so no nasty oil, vapours and gases for me thank you!
Not sure on all the K20's engine setup in terms of these systems, but if you can eliminate them, do it.