Thanks for the comments, eugenedakin and dude, even if they were almost depressing enough to make me want to slit my wrists...
Well, not really. So far I am just as out in left field as I was to begin with, but that's okay as I knew this was going to be a long shot in the first place (how's that for a mixed metaphor).
What I was envisioning was ignoring whatever woefully superannuated HPIB junk that might still be out there and instead "revinventing the wheel". More specifically, amplifying the mV signal from the FID - perhaps logarithmically, if necessary - then sampling it with an off-the-shelf A/D converter chip then presenting the digital output (time + magnitude) to, eg., a USB port. The hardware should be very much doable depending on what the actual signal output from an FID looks. Unfortunately, I haven't been able to find that sort of info out. Furthermore, as you pointed out, Dude, the software is inextricably linked to the detector to the a/d board, and while making the hardware would be trivial for me, writing the software would definitely not. Hey, I learned my lesson back when OS/2 Warp came out. I was so fired up about it but, damn, there wasn't hardly any good software available for it so I sat down to write my own e-mail client in REXX. Well, six months later I still hadn't even figured out the API hooks so I cut my losses and hung up my programming (dunce) cap right then and there. Not about to repeat that mistake again today.
Anyway, until I, a) find some hard data on FID output signal parameters; b) find a piece of 3rd party peak interpretation software that will (theoretically) work with whatever I concoct to interface it to the FID; c) or find someone else who had this same dim-bulb idea and met with success (or failure), I suppose I will have to shelve this one... is that the consensus thus far?
At any rate, eugenedakin, here's a link to the GC I was contemplating: http://www.srigc.com/2005catalog/cat33.htm
For a little more background on what I'm up to (and which might also help justify my selection of the "chemical engineering" forum), I want to test the ability of several ion exchange resins to perform acid-catalyzed esterification of the free fatty acids (typically oleic, linoleic and linolenic acids) in semi-refined vegetable oils. I have heard that Nafion might possibly be up to the task which would be a real hoot to me since Nafion is the darling polymer of the fuel cell crowd these days (I did *lots* of research in fuel cells a couple of years ago and concluded that they are way too ahead of their time from a lack of infrastructure, to say nothing of the cost of Pt or the polymers themselves).
Of course, the GC will also be used to certify the biodiesel meeting ASTM D-6584 (the specific subpart of D-6751 that calls for a GC), but as Dude pointed out, certification testing would be best left to a specialized analytical lab in the beginning, at least.
But anyway, back to the homebrewed GC to analyze homebrewed biodiesel... euegendakin, you mentioned that one of the handicaps of the 5880A was its low sample rate. I assume that this is the fault of the "Integrator" that interfaces with the unit and not with the FID itself. Please correct me if I am wrong, otherwise would it be safe to say that a higher sample rate of the FID output will result in substantially better accuracy?