I ran a stack injection system for 12 years, on the street and the track. I bought mine 14 years ago when 8 stack EFI was new and unique. I did most of the tuning and and mechanical work on it myself. The learning curve is a little steep. But if I can figure it, almost anyone can.
Webers are cool to look at. But its a carb. 4 of them. Carbs are old technology. If you plan driving the car in all kinds of weather and conditions, move in to the new century and go EFI. Even Harley's come with EFI now. EFI is more precise, easier to live with, pollutes less, and far easier to tune. Unless you're building an exact replica show car/trailer queen, there really is no good functional reason to use Weber carbs.
When you think of a stack system, you need to divide it up into about 3 functional components: the engine, the intake, and the computer. If they don't all match, it's not going to run well.
Remember that this is an individual runner intake system. There's no common plenum to draw air and fuel from. The IR is real sensitive to reversion, which is why you need a wide LSA. But, you also have to be careful about head selection. If your intake ports and valves are even a little bit too big the intake charge velocity will fall off, and you'll lose all of your low end power.
There is a plethora of computers available, from mild to wild. Pick the one that matches what you want to do. Some will include things like launch control, traction control, nitrous, turbos, etc. If you need all that extra racing capability, pay the money and get it now. But if not, look at the less complex and less expensive computers. Don't look at the bottom of the price scale, though. Those are mostly for 4 cylinder and batch fired engines. Although you can use them, they don't work that well and can be tough to work with. Megasquirt is an excellent middle of the road product that works well and has lots of support.
For the stacks themselves, pick a well known product from a vendor you trust. Good customer support is worth it's weight in gold. I wouldn't touch anything
from Speedmaster.
The linkage is extremely important. It has to be robust, and very adjustable. To get the balance right, you need to be able to make very fine adjustments, and it needs to be extremely accurate throughout it's range. If it isn't, it will never run right and no amount of tuning will ever fix it. I finally ended up tossing the supplied linkage and building my own from scratch.