The ReezaFRATzitz is a high gain overdrive/distortion circuit based around a CMOS chip, most likely a CD4069N or 74HCU04. This layout reflects a modded version by FreeStompboxes member thn.technik with added Bass and Mids controls. Here’s a link to his schematic and build pics. You might be able to squeeze it into 1590B, but you’d probably be more comfortable in a 1590BB. This is not originally a true-bypass effect. As you can see in the layout drawing, there is a “Clean Out” and a regular, or “Effect Out.” The signal comes in from the input jack directly to the board and into the buffer. From there a DPDT footswitch switches between the Clean Out and Effect Out. If you prefer true-byass, you can ignore the Clean Out pad and just wire this like you normally would. You can then eliminate the 150n cap and 470k resistor from the Clean Out pad. Here’s a demo of the original:
