AVR based PLC/relay board design

I need an AVR based PLC board designed. I am writing here Arduino Pins: ATMEGA328P with 16MHz crystal. The pins 0 & 1 are Rx and Tx respectively. I don't need an RS232 interface, just these TTL pins out. The pins 2 & 3 will be opto coupled inputs just like the PIC PLC board you make. The pins 4 will be out to a pin header, with VCC and GND. The pins 5,6,7,8, 10,11,12,13 goes to the ULN2803, the output of which goes to the 4 relays that are connected with 5,6,7,8. The rest 4 pins of the ULN2803 will just go to the Pin headers. The pin 9 will also go to a different pin header, like the pin 4 with its own VCC and GND. The A0, A1, A2 and A3 will again go out to a 4 pin header, with 4 rows of Vcc and GND. I would like a DS1307 RTC connected to the pins A4, A5 (SCL/SDA). Let me know, if you are interested, lets start will designing the schematics and PCB layout. The board will also have 7805 based power supply. The relays would be the normal 12V sugar cube relays, with 3 relays 10AMPS, and 1 relay 30AMPS. There is no need for USB, RS232, ISP pin headers, etc.