Hi Tom,
Yes, I can squeeze a new Vision stereo line board, Vision stereo phono board, new power supply board, and new toroid power transformer in you preamp chassis. Actually I could salvage and reuse your existing power supply board except that it won't provide the headphone performance of the new unit. The new power supply board has LME49600 buffer amplifiers built in to drive headphones.
The cost would be $699 for the line stage and power supply, $249 for the standard Vision phono, or $329 for the adjustable phono good for both MM and MC cartridges. You would save $50 if we recycle your power supply.
It appears that this unit has phase inverter circuits built into half of each line board. With the new circuits that would require an additional $199 board.
Regards,
Frank Van Alstine