I am currently fighting with this exact setup on my brothers cj-7 with AMC 258. It has been nothing but problems. I will list them to keep them organized as there are a few.
1. Proprietary parts - Injectors, TPS, Fuel pressure regu8lator ect. As far as I can tell these are not off shelf parts. If they are Holley will not assist you with finding replacements. They want you to send the whole thing back to them to "service " it. Which equals 2 weeks down time.
2. IT IS NOT PLUG AND PLAY! In the advertisements Holley states you don't need a computer to get this running. That is a blatant lie. Many of the features are not accessible from the touch screen. The software is not intuitive and will take you a long time to figure out if you have never messed with tuning software before. The manual does not go over the software at all.
3. We are currently using the negative side of the coil for a rpm signal and its shitty. Lots of guys out there having problems with electrical noise and interference causing it to run bad. To make this system work you need to drop another 1K+ into their special ignition system.
4. After we installed this on the jeep we had a hard timing getting it to start. Adjusted the fuel map a bunch and we got it starting and running ok. Randomly starting stalling when transitioning from throttle to idle. Over 2 weeks got worse then died completely. One injector was not spraying (both injectors should spray together). Injectors both tested good at 11 ohms. Wiring looked ok. i suspected a failed injector driver or computer. Called Holley and they wanted me to send it in to them for them to test. After initial communication a new in the box unit showed up with no explanation or communication. Installed new unit and the jeep starts on the initial fuel prime then stalled. It will not fuel after that initial start. I can jeep engine running with starting fluid. Holley is using the customer to R & D their product and they don't care how it screws over their customers. They know they have a problem but as far as I can see they have done nothing to fix it.
5. The computer is attached to the injection unit and is sealed with a resin of sorts so you cannot inspect the board. All so exposes the board to a lot of heat, moisture and vibration. Terrible engineering in my opinion.
6. The injectors feed into two rings that have a few tiny holes drilled into them in a poor attempt at better atomization. This is a lost cause as the injection holes are ABOVE the throttle blades. So the fuel just puddles on the throttle blades at idle anyways.
If there is a OEM injection manifold (or you can modify the carb manifold to accept injectors) then this is the way to go. Your going to have to learn how to tune anyways so you may as well build a Mega squirt engine management system for it. In the end you will be WAY ahead in money spent and you can get off the shelf parts to fix it when the need arises.
Hope this helps lol
Edited- Got the cj-7 running. Turns out we had a bad load of gas. My brother filled the tank up right before it started giving us trouble. Drained and refilled with good fuel and it fired right up. We ended up using the Holley hyperspark distributor instead of the stock coil. Fires right up and so far has been running good without any more problems.
5. After it is all said and done you will spend the same or more to get it running right then you will spend on a proper high end fuel injection system. You are getting what you pay for here.