IAT placement for ITB applications is not very critical tbh, just as long as it isn't sitting next to a considerably hotter or colder thing in the engine bay. I was going to plumb it into one of the runners but ended up just tying it down between the number 2 and 3 horns. if you look carefully in the picture above the dyno chart, you can see the tip and the one of the screw holes of a stock sensor. in a naturally aspirated application, anywhere in the intake tract would work (think ek civic and its push in style IAT).
emissions is not an issue here in hawaii, so as a general rule of thumb i vent all pcv outlets to atmosphere. clean manifolds are happy manifolds. not to mention it would take quite a lot to get an open ITB setup past a sniffer, let alone a visual. i would assume a one-off carbon manifold would be in the same category as well? or are the cars so old they are exempt in your neck of the woods?
as for an IACV, i tried plumbing an obd1 valve into the vacuum block on the firewall at first. i then found out two things: 1- there isnt enough flow to properly control idle through one vacuum line, as the valve is not fast enough or close enough to the runners to make it work properly. 2- there is definitely enough flow through one vacuum line to make the idle unstable, and more importantly take all the vacuum away from the booster and make racing the car both unpleasant and unpredictable (having no plenum to pull vacuum means there is very little to begin with). i understand why people use unassisted brake systems, and if i spent enough time and money i could get it to work. that being said, i like a short pedal that requires less effort as i am fighting the no power steering battle irregardless. i contemplated a vacuum can to help the booster, but things seem to work well enough as is so it is not going to be changed anytime soon. as a bonus, the MAP sensor can now see when the little amount of vacuum available is being drawn. with a manifold sporting a plenum, you could probably get a decent idle mechanically with throttle plate adjustment assuming the weather stays roughly the same every time you drive the car. i tapped one side of the valve to feed the vacuum block, so it should work if plumbed into a plenum as well. if disabling the IACV is not an option, you could just leave it plugged in to avoid a code and work around it.
TL;DR- IACV is disabled in the hondata calibration, MAP is not needed for alpha-n tuning. plumbing a valve isnt impossible but only worth the effort with a plenum.
if i had to do it again, i would consider a cheddas adapter plate and a y8 manifold. supercharger would be nice as well, but i think the firewall would need a lot of massaging. cheap ITB sets are over 500 so i wouldnt buy even the obx stuff. no matter what combination it ends up being, obd1 is key. must have. dont skimp. support souza speed. second best money spent on the car ever, right after the teins-