The LG4 doesn't have fuel injection; it's the base-model low-output computer-controlled carb system. We're working with a computer-controlled Q-Jet system here.
On the LG4, if you set the static timing to its spec (0°) it will most likely have only about 28° of "total" timing measured the same way you'd check a mechanically controlled distributor.... the "spec" is influenced by emissions levels, not just as the engine's "ideal" "best power" requirements or even "best economy". Just because you can look up in "the book" and find a "spec", does not necessarily mean that it's the "best possible" setting; the factory has too many other purposes that the "spec" serves, not all of which are the same as yours. Instead of slaving yourself to "the spec", give the engine what it wants.
As stated, in the electronic system, the distributor itself is totally fixed at one point, with no physical advance occurring either due to RPM or vacuum. Rather, the ECM examines the engine's operating conditions (throttle position, RPM, MAP/vacuum, coolant temp, O2 sensor indication, etc. etc. etc.) and looks up in a table of values programmed into it, what the "correct" advance should be, for that specific set of conditions; and applies it electronically. You can't easily change those values in that old crude Stone Age computer, not like you can with the newer ones; which is why the easiest thing to do to improve its performance is to set the static timing to the point at which the "total" timing, checked under the same set of conditions you'd check a mech dist under, is where it needs to be (36-38° or so). As also previously stated, more than likely that will produce a static timing setting of around 8-10°, with the factory LG4 programming.
The computer controls the TCC. It requires a list of inputs to do that accurately; throttle position, vacuum/MAP, vehicle speed, coolant temp, brake status, and so forth. Clearly, if the ECM is removed, it can no longer control anything; and if any of those inputs are missing (particularly throttle position, which is a part of the carb), then it can't do it either. The "kits" that you can buy are pretty crude and brute-force. About all they do is make it to where you can tell yourself "yeah the TCC comes on sometimes". It's FAR FROM as sophisticated as the computer, even as basic and minimal as that computer system is.
If there's no good reason to hack the ECM system off, resist the temptation. Like I said, on a stock or near-stock motor, NO OTHER carb and dist is going to really make much difference as far as making more power, because that's not what limits that motor's potential. As we all know, the way to make a car go faster, is NOT to just un-bolt and re-bolt the big shiny things that sit up on top, out in the open where everybody can see; the only way that doing that will make the car faster, is by weight reduction, with all reductions applied exclusively to the driver's wallet.
The CORRECT mental approach to modding a car is to look at THE CAR (not just the "engine"), and find the ONE THING that's most slowing it down, and apply a properly chosen, compatible modification to THAT THING. That will then expose some other thing as the next ONE THING that most slows the car down, and you then do the same to that thing. In the LG4, those things are, in order of importance, the exhaust first (which you're dealing with), then the programming (which the L69 version is MUCH better and is very easy to get and install), then the cam, then the gears, then the torque converter, then the compression, then the heads. Somewhere along the line it needs a better air cleaner too, preferably NOT an open element, in spite of the gratifying additional noise it makes which does nothing at all for power but merely recalibrates the driver's "butt dyno" (usually in fact leaves power on the table, because it picks up hot thin air instead of cold dense air).
Then and only then, MAYBE, after ALL that other stuff is changed, a carb swap will do something productive. Until then, you'll get FAR MORE bang for the buck, by repairing, tuning and working WITH the stuff that's there, rather than just indiscriminately hacking it all off, like illiterate newbies do in the name of "cleaning up the engine bay" or "what emissions crap do I not need". Make an effort to understand how the computer works, and use it to your advantage. In particular, it's good for around 20%, or more, of fuel economy, compared to a typical Edelbrock (Carter) carb or the like. Add that expense in to whatever cost calculations the owner is making, and suddenly all that hacking isn't near as attractive-looking. Personally I'll take a few hoses and wires snaking around on an engine that nobody ever sees, in exchange for a constant and permanent cash flow burden of $10 or $15 or $40 or whatever per week, in increased fuel cost.
Also as stated before, the whole computer system will work fine on a 327 or 350 with almost no modification whatsoever, IF the cam is chosen accordingly. If the car's owner isn't looking to race the car, that's still not a reason to hack the factory stuff off. Use it to his advantage.