Here's my methodology. I hate making too many changes at once because if the end result has an issue, it's hard to track down what the issue is when you've changed so many things at once. I'm an engineer by trade, and often times I have to figure out why the sudden something isn't working and my first question is "what did you change" to which I often get a long list of things. Change one thing...validate it.
With that said, there are issues that can sometimes arise with aftermarket calibrated MAF's. There can also be issues that arise with intake swaps (intake gasket slips leading to a vac leak and idle surge or backfire). Now you throw a TB on there, some other mods and all the sudden you have a surging idle. Well, do you pull the intake off and reseat it? Or do you troubleshoot the MAF and try and see if that calibrated MAF is causing it.
Here's what I would do in your shoes...hear me out.
Sn95 MAF. Grad one on ebay, or even look on rockauto.com. (I see a new cardone unit for $55). You'll need an adapter, or perhaps you have a custom intake that will work with the 4-bolt flange style MAF. Install that. Get it running.
I forget if you had the GT4oP's already on or not, but next up I'd do the heads and intake (and cam if you have it). Get that buttoned up. Make sure the car is running well. Idles well, no surging, no codes.
Now, if you insist on a tune at this point, hop on the classifieds and pick up a set of EV1 24# injectors. They were made for so many years that they are plentiful in good used shape. Set up your tune appt. Couple days before, swap in the 24# injectors. Car will run fine. The ECU will shorten the duty cycle to compensate but you may run pig rich at WOT. That's fine as you just need to get to the dyno. Have them tune the car with 24# injectors and call it a day. Or, if possible, make a run on the 19's and then install the 24's based on what you see there.
Now, you certainly can do the other things you are listing out. You can solder on EV6 harnesses and run those with a calibrated MAF, but it's not necessary. 1993 Cobras did have 24's, but that was also a production car that Ford had to build to last a long time and make it to 100K+ miles. They built in a little reliability to avoid warranty claims when injectors crap out on them. Usually most enthusiasts here aren't driving their car every day (maybe you are who knows), and can also swap out a single injector if one fails.
Entirely your decision to make as to what you do and we will continue to answer your questions, but just consider simplifying things a tad.
