One type is a flat bed in which the pen is moved in an X and Y axis. This was the traditional approach to making a plotter. The other type of plotter is or was a drum plotter. In this type of unit, the pen moved in the X anis and the paper moved in the Y axis. I haven't seen a drum plotter for a number of years.
Some plotters work like a drum but with no drum.
The paper is moved in the Y axis and the pen in the X axis. Using this approach it has been easy to build B size units that can draw on 11X17 paper. Because there are no arms it might be easier to adapt a unit in which the paper moves. I would also suggest that instead of a spur wheel that a reciprocating pin be used. This would solve the problem of too tight a curve.