I am building an 8 stack EFI system for my 351C using an old Redline IDA intake, some 25mm adapter plates I fabricated, and 8 aftermarket IDA lookalike EFI throttle bodies. I will run a Mustang sequential speed density (DA1) ecu with quarterhorse to tune. I am seeking input on a couple of aspects.

I can run the IDA TB's with the injectors inboard of the TB's which gives a nice line of sight right into the head intake port (about 45° from vertical, injectors pointing outwards from engine certerline). Or I can have the injectors outboard of the TB's so the injectors spray across the airflow path (about 45° from vertical, injectors pointing inwards). I have seen both of these injector locations used in different aftermarket IR EFI setups. My gut says to go with the inboard injector location to get the clearest shot at the intake valve. Any thoughts?

I have a 460 TFI distributor from a 1989 F150. This has the TFI module on the distributor and uses the standard 6 pin hookup. But the HE sensor is not linked to the TFI module inside the distrubutor like it is for the 5.0's, instead there is an extra 7 pin plug that comes out of the distributor (I'm not sure what the other 4 wires actually do). I was thinking that I would use a 5.0 distributor housing and install the 460 shaft. This will then be directly compatible with a standard 5.0 wiring harness. Any thoughts?

I'd go the inboard injector shot to hit the back of the valve.
You may need to make a "manifold" for your MAP sensor to get a good signal.
That dizzy sounds like someone banged a TFI module on it because the round connector is for use with a remote TFI that the 7.5L engines used.
This should explain it....
https://www.supermotors.net/getfile/897 ... -mount.jpg

Yes, I had planned a manifold for vacuum signal. Each adapter plate will have 1/4" vacuum fitting with silicone pipe connecting to vacuum manifold. The silicone pipes can be individually removed from the manifold and run to a vacuum gauge(s) to initially balance the TB's.

The dizzy has a 1989 assembly sticker (March 89), and the TFI module has a similar manufacture date (Feb 89). I have read that early EFI 460's used a dizzy mounted TFI, before moving to remote mount to counter heat soak issues. My preference is dizzy mounted for wiring simplicity, hence why I am favouring the 5.0 dizzy body swap. I assume the remote mount TFI modules are identical to dizzy mounted ie. so I could remote mount a 5.0 TFI on a big heatsink if I wanted to

Thanks for that link, explains the plug. RJM technologies....... Is Ryan still operating somewhere?? The internet is littered with bad comments about failing to ship purchased products 6-18 months ago, and both his web sites are now pending authentication or something similar. He did make very nice EFI harnesses, I picked up a NOS 5.0 locally and was very impressed with the identification writing printed on the insulation of each wire.

can you get the injectors inboard? i know on mine theres not enough room to get injectors and rails in between the banks

BTW speed density wont work on ITB's you need an ecu capable of primarily AN tuning along with MAP correction

I have about an inch between the fuel rails, so it should clear OK.

Interesting comment about Alpha N v's SD. Why is this the situation? I'm guessing it's something to do with lack of manifold runner/plunum volume?? Any other hints or tips on this project much appreciated since you've already been there, done that

I'm still keen to give SD a whirl as I've already got a couple of QH's and the SD ecu & wiring harnesses. Just need to buy the strategy from Derek (Sailorbob) which was only $25 when I inquired.

SD can be problematic but I've seen an IR 460 run with it very nicely with a little Vac plenum as you describe and it wasn't a little stick in it either.
Dereks DEF's are a bargain for sure. I think I'll get him to a do an SD bank E9D1 (5.8 F-series with a great Lean cruise strategy) to try on my Range Rover if I don't go the whole hog with a PCM-122 from a BA 3V.

Sd won't fuel correctly due to low vac where as AN will. Ive Got mine setup with dual maps SD at under 80kpa / 15% tps and AN with map correction above that