Thanks to everyone who helped me with images and suggestions for a cabinet to complement my Concert Bass head.
I decided on the 115V, and built the following cabinet from a combination of the specs on the catalog page and the image you sent.
Without specific interior dimensions, it's surely less than a perfect knockoff, but it looks good to me and should do nicely with the Legend 15 CB158.
Front View 115V
Rear View w/Back
Front View w/ Grille Frame
I have the speaker, Tolex, grille cloth, corners, casters and all the stainless fasteners to complete the cabinet, even a set of original Sunn jack cups. I'll post more images when the job is finished and the Concert Bass head is sitting on top of it.
I've also finished the construction of the two 2000S cabinets that I wanted for my 2000S head. The original drawings are available from Conrad for $35. Images for these cabinets are in a separate thread.
Thanks again to everyone else who helped me make the 115V decision.