Yeah, you're right. Exact tuning isn't anywhere near as useful as a VAFC/SAFC. Again, welcome to 2007.
The fuel cutoff for D16s is at 7600rpm for a reason. An accidental rev to 8200rpm will, more likely than not, float a valve and cause some internal engine damage. Totally worth being a cheap-ass.
The cost of an OBDI conversion depends on how much you can do yourself and whether or not you get a distributor with the head. It cost $250 for a VAFC, or $105 for an OBDI conversion harness, $120 for a P28, and $80 for a 4-wire O2 sensor. It isn't that much more expensive.
You go ahead and take this personally, because I'm not.