The Wiki seems to think the original 8250 had some bad bugs, and seems to be recommending the debugged version. The 8250B, instead.
https://en.wikipedia.org/wiki/8250_UARTThe chip designations carry suffix letters for later versions of the same chip series. For example, the original 8250 was soon followed by the 8250A and 8250B versions that corrected some bugs. In particular, the original 8250 could repeat transmission of a character if the CTS line was asserted asynchronously during the first transmission attempt.
The +5 and GND power pins are apparently open circuit.
I'd be tempted to connect the /RI pin up to the RS232, using the (spare) available gates, for completeness.
Transferring long serial files, can take a boringly/annoyingly long time. Especially when you need to do it LOTS of times. Therefore:
The 3.072 MHz will work perfectly fine, up to about 38 Kbaud.
BUT if you went with the 8 MHz, it will still do all (or just about all), the baud rates up to 38 Kbaud.
But then, would also do much higher (such as about 3x faster), rates. Depending on what max baud rate you can sync up with, as regards the other end (PC ?).
tl;dr
Seriously consider an 8 MHz crystal (unless you need/want software compatibility with 3.072 MHz clock divider bit settings). Since it apparently will give you just about all the rates the 3.072 MHz would have given you, AND the options on much faster ones, which go to at least slightly more than three times faster.
For quick test development work, it can be more pleasant for the download/upload etc, to take 1 minute, rather than 3 minutes, unless you like drinking coffee, every 5..10 minutes (Joke).
Another ideaIf you are planning on developing the code for the ROMS, yourself. I.e. you are going to keep on iteratively changing it, while writing the software. You may want to create a "ROM emulator/simulator" card.
Which uses CMOS battery backed up RAM, with write protect, and read(?)/write access via external serial interface.
This is to avoid having to continually program/erase (in a UV eraser) and change the ZIP socketed 2764's. On a regular basis.
Alternatively you could (temporarily) use flash devices, until your software (for the ROMS), is finalized.
But don't worry. Using actual EPROMS is not the end of the world, and perfectly viable. One gets use to keeping a pile of 2764's (in your case) in the UV eraser, and get use to swapping them between the erase, burner and development board(s).