The images below show my version of a tube adapter which can be used on breadboards.
Select the length of the M3-screws such that the small board is as horizontal as possible if it is used with your board.
Finally find the schematic (a PCL86 tube was taken as example - see also PCL86 Amplifier) and the layout as images below. The EAGLE schematic file can be downloded here and the board-file for the layout here.