Vaccum lines and new air filter

[nsmngr]

I'm new to the Datsun world and just purchased my first one being a 1973 Datsun 620 with a 1.6L.  It was backfiring when I got it home and tracked it down to several disconnected vacuum lines which I hooked back up and/or plugged.  This solved the problem.  The stock air cleaner seems very restrictive so I am planning to replace the entire unit with an open air K&N style element.  I've seen several pics that look like a square air cleaner and filter is used.  Can someone point me in the direction where to purchase this?  Also, since this vehicle is exempt from smog, I plan to remove the many vacuum lines.  Other than the one to the vacuum advance on the distributor are there any other lines I should keep.  Where should I attach the blow-by line?  I think I saw a filter that is sold for this so I'm assuming I can install that to take care of this.  Thanks for your help.