It is a bit of "brute force", but the easiest way is to simply transfer the contents of the files using the REPO FORM (report form) command in Metropolis to send them to a serial port... With only the table name, it will do the equivalent of an SQL "SELECT * FROM " command. Since nearly all of the serial printers of those days literally took ASCII and splattered it across the page, this command results in the contents of the data file gushing out the serial port, ready for capture as a text file!
Since very few of these systems had even rudimentary referential integrity or enough raw data to make a significant amount of work by today's standards, it shouldn't be tough to simply plunk the data into files or tables and "start cooking" a web app.
Man, talk about "deja vu all over again"... This brings back all kinds of memories.
Where the heck are these systems? Just FYI, at one time both BCS (the Boston Computer Society) and the Museum of Science and Industry (in Chicago) were looking for systems of that vintage... They may have some significant
PR value if you choose to donate them.
-PatP