Hi Brian,
A lot of LisaBBS is Lisa-specific. The 68K assembly code is not going to work on ARM, of course, and all the code that talks to the filesystem or works with the serial port targets Lisa OS specifically. Additionally, some of the data that LisaBBS packages in archives that it sends (e.g. the 128k of "label" data, plus some of the filesystem metadata) has no counterpart on a Linux box.
There may be an additional problem for would-be porters. Lisa Pascal supports arguments to functions and procedures that are also functions and procedures. I don't know if Free Pascal does this---I'm not sure, but I get the impression that this capability isn't found in most Pascal compilers. (Disclaimer: I've only ever written Pascal code for the Lisa---and the computer science AP test back in the 1990s :-)
The implementation of quicksort uses function and procedure arguments pretty extensively, see
They turn up elsewhere, too.
Fortunately, there's little point to porting LisaBBS to a modern computer running any sort of Linux. You would be much better off writing a very thin Pascal shell (or Python would be even easier) that mimics the simplistic LisaBBS interface and invokes
lrzsz to send files to the remote system.