Wow, you do have a very obsolete PLC! From what I can find out this model was first introduced in 1982 and replaced in 1986 with Sharp support for the ZV series terminating in 1993. I had hoped to help you with spare modules removed from equipment we have replaced but your ZV series predates anything I have.
Sharp is sold, supported and used in the United States with its market typically being Japanese companies. Here at Sony we have a large installed base of ZW and JW Sharp PLCs and for sales and support we use the following company:
OTEC (Ohio Takamatsu Electric Company)
Ph: 614.438.0222
Judging by what you have listed your system has 16 inputs and 32 outputs maximum, a very small system by today's standards. Given that you have both the schematics and ladder logic for your HAST chamber, you should be able to select a small PLC to replace the Sharp ZV and install it.
As far as a plan of attack, I would now research available PLCs and select a suitable replacement. If you want service and support I would purchase the PLC from a distributor. If you feel comfortable supporting yourself and want to save money, you can turn to the equipment liquidation/salvage market or even Ebay to purchase the PLC.
After purchasing a replacement PLC, set it up on a bench, program and test it to confirm it is working as expected. Completely back-up your Sharp PLC to protect your investment should your installation not function as expected, the Sharp can be reinstalled. Remove the Sharp PLC and install its replacement, debug the program you have copied from the Sharp and you should now have an updated HAST chamber.
Good luck!