if you need two cpu's I'd make one a raspberrypi , honestly multi gigabyte sd cards ,usb sticks, wifi ,Ethernet 512meg of ram and the elegant simplicity of python scripts and sql databases.
bang a pic on the side for lowdown nuts and bolts real time interfacing . join them together with rs232,spi,i2c what ever you like and bobs your uncle. multitasking (threading ) with python is just wonderful and have a look at pigpio by joan for some lowlevel stuff if you like (pretty amazing),but I still prefer bit-banging with a PIC.
why struggle when you can overkill it to death