The Dr. Boogie is a JFET-based amp emulator of the Mesa Boogie Dual Rectifier Solo head, designed by ElectraTabs over on the DIYStompboxes forum. It creates a unique high-gain distortion effect.
Most layouts and builds of this effect I've seen are in 1590BB enclosures. This one should fit in a 1590B, but would probably be more comfortable in a 125B. Use right angle PCB mount pots and mount them to the board from the solder-side. Mind the EQ row of pots are oriented 180º differently from the top row of pots.