What wideband is it? Typically they give you the software.
You could try you put something together with an arduino board, but to make loggign useful it has to include at least rpm, throttle position and preferably boost.
Rather than run 2, here's another budget idea. Chop up a stock afm and put it into a larger pipe, maybe 3.5 or 4 inch.
I saw a pic of a z32 cut up and put into a pipe, will try to find it again.
It's not like you are actually looking for a better way, you are just looking for one that works in your case
Can't you just get the correct block? Have you seen when guys have made a plate to go where the idler should be?