As long as you guys choose to go with EFI systems that essentially provide a carburetor to EFI conversion using what looks like the old carburetor, you are going to be working with a compromise at best. You should be using individual port injectors, a EFI specific manifold designed for dry operation and a suitable throttle body for the airflow your particular engine demands.
You have three fueling strategies available to you Alpha -N, Speed Density and MAF based in order of increasing sophistication. By far the most popular systems are speed density systems. MAF based systems are the most precise in matching fuel delivery to air flow. Alpha-N strategies are regularly incorporated into both the speed density and MAF based models.
Speed density systems ignore actual air flow and calculated an implied mass air flow from manifold pressure, throttle position and air temps. The MAF based systems precisely measure air flow with their MAF and calculate fuel demand based on injested air mass and engine load. MAF stuff works everywhere, Speed Density works well unless there are significant atmospheric changes or altitude changes.
The auto learning functions allow you to get "close" to the right tune but still require programming intervention to get it right everywhere, always, all the time. Buying low cost good enough systems usually are not either low cost nor good enough to get the job done correctly. If you have the skills then you can learn how to tune one if you don't, step back and buy the expertise form a reputable tuning shop familiar with your EFI choice.
In terms of bang for the buck you can not beat the manufactured Megasquirt MS3Pro-Ultimate systems from
DIYAutoTune <= clickable. This particular EFI system is the equivalent of a Haltech or similar system costing 2-3x the price. Additionally the Megasquirt guys are among the very oldest of all the aftermarket EFI providers — their stuff has years of service and debugging work already done when you buy it. Did I mention they come with a lifetime warranty? Nice thing to have when something goes bump in the dark.
You can learn how to tune it but you can also go to a shop to buy the tuning skills for your install. Unlike most EFI systems that require you to buy 'their sensors' the Megasquirt guys allow calibrating the EFI system to work with any sensor you want to use — including the cheapo sensor form the local parts store (not recommended).
Don't use a wet flow manifold with a dry flow EFI system. Seems like it ought to work and it will but you will loose tunability especially when you start to hunt for ways to bolster the torque in some rpm ranges where you want more grunt. Buy a good aftermarket manifold that was designed as a dry flow manifold from the ground up. If there are no commercial alternatives available look for the older cross ram style individual runner manifolds (ideally with adjustable runner lengths) and weld injector bungs to them at the ports.
Remember the self learning systems are designed to get you running, probably work OK for a grocery getter but will fall short of the mark for a performance application. For performance applications you will need to actually tune your EFI system yourself or buy the service form a good shop.
If you go cheap (low quality not necessarily price) you will go back to the mat more than one time before you are done. Save yourself the headache of the looks like a carb but is really EFI alternatives. At best they are bad compromises, at worst they are useless headaches and a money pit waste of money.
Ed