Opinions and advice trans and ecu swap EJ8

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Okay so I have been reading for countless hours on the task of a 5 spd conversion on a civic and I plan to do this very soon but I want to make sure I have all of my ducks in a row perfectly first... I believe I want to use the S40 trans... if im not mistaken its a little closer ratio than the S20..?.. and the only real question left is P2M P2P or P28 ecu (or any other ecu preference welcomed) what will give me the most out of a D16y8 ... im not trying to build a monster here I just want something to have some fun in the north GA mountains and do it on a budget.... I have a little more than mildly but nothing any where near extremely ported and polished head, b18b1 ls throttle body and a full exhaust and in the near future I want to raise the compression from 9.6:1 to around 10-10.5 maybe 11:1 but probably not since I want to try to keep a stockish brain... will any other stock cams be a good swap or no and if anyone has any other tips on doing the 5spd conv. it would be very much appreciated as with any information... im a rotary guy and this is only my second civic build and first 5spd conversion and my ocd just has to have everything in order before I start... thank you so much for your time in advance
p28 is what you want to use most likely. its the obd1 predecessor/equiv of the y8 from the d16z6. you CAN make your own automatic ecu manual, though, and that may be the smarter thing to do if you are handy with a solder/de-solder gun.
https://hondaswap.com/~pills/autotomanual.html for info

they y8 has the 'best' factory stuff on it already (cam, intake manifold) so you're going to have to go to the next step if you want more gains. I'd suggest the full ihe routine first though.

there's many varieties of s40 and s20's out there, it's really hard to know what you're going to end up with... The good news is that they are not very different, very subtle.
intake header exhaust??? not sure on that abbreviation and thanks for link ill most likely be doing that to the p28 I have in the garage from my old z6 when I went " you cant shift faster than a matic" and it ended in catastrophic failure... as far as the trans the s40 has the steel shift fork and if in a ex it has the 4.25 final correct or no?
yes, intake/header/exhaust

I'm not up on d-series trannies these days, not sure.
gotcha sorry for the noobness ...already on top of that ractive headers 4-2-1 straight back to a dc can and a 3in long ram im bending myself pic only shows the top half