Updated: May 5, 2021
Ceriatone's Centura documentation assists in figuring out the original Centaur's resistor types (Metal film/Ceramic) in their proper location. The PCB is the fantastic Aion Electronics Refractor PCB. The diodes in this build is 60's NOS Sylvania 1N394 which forward voltage metered out around .38vf. The result is a near 1:1 tone of the original Klon in my opinion :-)
Going with the bigger enclosure, I was able to fit SwitchCraft #111x enclosed jacks at the top which helps save some room on the pedal board and I'm able to swap between the Klon enclosure and the smaller one :-). Because all the mojo of the original Klon is in the ribbon cable, I added this ribbon cable internally between the stomp switch PCB and the main board. Visually speaking, the internals has a lot of cues of the original which I think is neat.
For external esthetics:
Aion Refractor: https://aionelectronics.com/project/refractor-centaur-overdrive/ Ceriatone Centura Documentation: http://www.ceriatone.com/centura-professional-overdrive/
Gear used in this build: http://amzn.to/2eFxEfj PCB Holder http://amzn.to/2upePRL red lead forming tool http://amzn.to/2un7nrQ 60/40 solder http://amzn.to/2upj6Ez solder tip cleaning http://amzn.to/2uMRE6n recommended soldering iron