I was just given a 17056281 carburetor.  A  quick look reveals it's a 800 cfm unit with large air bleeds.  It shows the "APT plug" on top just like a 1979 and 1980 carburetor I have.  Do I understand it's a "good APT" carb and not a "less desirable" 75 and some 76 units ?  Also noticed the idle air bypass holes seem quite big, around .110".  Is this too big ?  This is probably going to go on a very mild 250 hp or so 350.   This may see future use on a 375 or so HP 400 small block.  Is this a good carb to rebuild and later "resize" for bigger motor ?  I have Cliff's book and read it cover to cover many times, as well as Doug Roe's book on Rochester carb.