The parport system is all cjb's and I haven't set it up here yet at House Harris so I'm not familiar with all the details and he's taken off on a motorbike tour of the country.
It's definitely an 8 data bit protocol and would no doubt be easily adaptable to your BBC if it has a 6522 controlled printer port. I use ser2net myself for communication with the SYM-1 but it's a vector redirect to point the I/O to the parport interface instead much the same as your BBC by the sounds of it and I'm confident that some study of the code could have it running with it.
I don't expect I'd need elaborate on the speed and reliability increases that it would provide to you, and myself when I get down to setting it up here.
6502.org
The 6502 Microprocessor Resource