Chevymanty

I am bldg new construction w/my 4.8 and 4L60E trans- Questions: I'm looking at a used B&M Shifter w/cable, do I have to just install Shifter where I want then run cable and adjust of course to my trans lever then good to go? 2nd Question: From my manifold I ran 2 1/4 " pipe about 1 1/2ft long which I want to attach to existing 1 3/4" pipe, since dropping down 1/2" will I have any issues?, This is only to drive around town etc not the Strip! Thx Advise! Dana