Edit: This message is deprecated. I'm not happy with this solution. Original follows:
Ok, thx, that is encouraging.
Here is a picture of this very simple procedure (not a FL board) if anyone else thinks they have peak and hold and wants to try it. Please report your findings if you do. You can identify peak and hold by unplugging an injector and measuring the injector with an ohmmeter (2-7 ohms is peak and hold, 10-15 is saturation), they are in a fairly small percentage of cars these days, mostly from the late 80s and early 90s from what I can gather:
The zener in question on the spiffed board is the lower right one in this picture (I think):
kits:mpguino:04_place_220.jpg [SpiffieWiki]
Here is a source for the resistor used in this circumstance:
22K Ohm 1/4-Watt Carbon Film Resistor (5-Pack) - RadioShack.com
It could be added as an optional resistor to the schematic, not sure what to do with the pre-assembled units I'm planning on. It makes the signal on a saturated injection system less definite, and those seem to be in the majority so maybe I have to add some questions to the ordering process, and possibly add a jumper to the next revision.