Berettaboi is right regarding the Quad-4 forums being your best source, but I've done more than a little work on the 2.3s and 2.4s, including mix/match/hybrid work on them. Specifically, I put a 2.3 Quad with a 2.4 Twin Cam head into my '97 Z-24 five-speed (now '01 higher-compression 2.4 Twin Cam intercooled turbo) car for about a year.
So, yes, your 2.4 Twin Cam computer will run the 2.3 Quad engine, but it may not do it optimally. Unless you are swapping heads (or at least cam-carriers), you will lose the direct-drive power-steering pump setup that the 2.4 uses, which IMO was the best change GM made to the engine design going from the 2.3 to the 2.4. In '98, the Twin Cam should still be using 'conventional' (non- low impedance) fuel injectors, so the ECM might run the 2.3's injectors fine, but I would plan on swapping the 2.4's back on anyway, at least give yourself that option in case it doesn't run quite right. The small displacement change might cause tuning problems, or even cause your car to run a little rich, but it should still run fine if you can pass through emissions (if applicable). Engine accessories, such as the alternator, will not bolt directly up, so you will need to retain the 2.3's accessories, and the alternator's field-circuit wire is different, so you will need to spike that off from a different source (I used the ICM's ignition power-lead to energize my alternator). It has been several years, but I don't think there was much else that had to be swapped-over. I do remember messing with the water-pump to make the 2.4's pump work on the 2.3's block, but that was because my 2.3 was originally a SOHC, so I couldn't retain the timing-case for use with the 2.4's head, and the 2.4 drives the water-pump directly off of the timing chain (very stupid, since you have to break into the timing-case to replace the water-pump), rather than using the intermediate shaft and bearing that the older 2.3's used. Going from a 2.4 to a 2.3 H.O. Quad, or ANY 16v DOHC Quad, you shouldn't have a problem. Heater-hoses might not plug straight in, I don't recal having any issues though, and radiator hoses are plug-and-play. Honestly, I'm not 100% certain regarding the cam position sensor, but the Quad forums should be able to answer that. Throttle-body locations are different, but a CAI will negate that issue, I don't know about exhaust manifolds vs exhaust pipe flange mounts, but I can't imagine that would be much of an issue if you are already going through the trouble of an engine-swap.
Or you could just turbo-charge your 2.4, it worked for me, and my little '97 Z will totally decimate my '89 Camaro RS 5-speed Police Special 350 car, at least up to highway speeds. In fact, it almost keeps up with my 3800 SC 5-speed GTU up to 80 mph.
- '97 Z-24, notice the fender is the only clean spot on the car, because the steel Z-3 fenders are new!
- The intercooler is small, but so is the IHI turbo feeding into it. It receives cold air directly from the functional hood scoop.
<Edit: the knock-sensor isn't compatible on some year 2.4s vs the 2.3, so you may have to find another place to mount that in, too.>