<p>What you need is :<br>
RZ body - either Pro 1 or Pro II will do, I'd say condition is more important<br>
RZ back - 120 film has many more choice available - black and white and transparency - a 120 back.<br>
Finder - waist level finder is most basic, often comes with a used body, and can work fine for portraits<br>
Lens - RZ lens, go by focal length you prefer, roughly equivalent focal length is 2x to 35mm, i.e. the 180mm RZ lens is kind of like a 90mm on 35mm full frame although the aspect ratio is different. The 180 regular lens is pretty cheap in general, the 110 is very nice, but more like a 55mm lens.</p>
<p>Some way to meter the exposure - a DSLR set to the same film speed can be used.</p>
<p>Lighting - whatever you want - </p>