I've find a good portion of what I'd like to know but overall I want just a little more clarification on this subject. Any help is very much appreciated!
I own a series 4, 6 port NA. Naturally I'm urged to move forward with something a little better, after going around and around in circles with the "6 port Tii" vs "turbo-NA" I have decided to go the way of a 6 port Tii set up. One of the main reasons for this is that eventually I want to BNR upgrade the s5 turbo I have sourced and with already very minor clearing between the 6 port LIM, this won't be possible without notching my frame which I am not interested in doing.
Now, I have a lead on an inexpensive used t2 intake setup and after seeing the process of combining the outer ports the question popped into my head.. Is it possible to simply swap the front / rear irons to a 4 port turbo set in lieu of modifying the LIM. This gives me a bit more room for porting and eases my OCD knowing the intake mates up perfectly.
I just need some clarification that all else will line up such as coolant passages etc. Would it be necessary to get s4 turbo irons or will either series work?

I have compression tested my engine and the rear rotor numbers were a little low, so I already plan to pull the engine and rebuild myself, I have also seen very affordable turbo irons for sale.. When I read over doing the 6 port swap people always make the statement of it being way cheaper to just buy a full t2 engine. These threads are many years old though, I've scoured high and low on local rotary pages and classified sites every day for a solid year and haven't seen a full swap sell for less then 2000$, not to mention more than likely needing to rebuild it as well.
This is the route I would prefer to take if it is possible, It gives me the ability to slowly acquire what I need as it pops up and also lets me keep my original 13b (for the most part) alive. Thank you for reading over this and for any knowledge you have to share with me on this subject! Cheers.

 

There are some different options for you. First you can use the S4 turbo irons if you like. It will make some of the turbo install down the road easier as far as the oil feed to the turbo, intake setup, etc. Power wise I'm not sure where it would be. A stock ported TII motor being run n/a may make less power than the 6-port. The TII LIM is bad for flow due to the sharp bends it makes to clear the turbo. That said I've read on here a street ported 4-port motor makes better power than the 6-ports, but that's not using a TII LIM. What you could do is streetport the TII irons and port match the 6-port LIM and run that setup until the day you go turbo. If you got a standalone ecu I'm pretty sure that setup could be tuned to make decent power for a n/a. You should at least be able to make more at the wheels than the stock 6-port made at the flywheel.

Also if possible it would be a good idea to either switch to TII rotor housings or switch the exhaust inserts in the exhaust ports out to TII inserts. Getting rid of those diffusers helps as it allows you to be able to street port the exhaust.
Porting 86-92 6-Port Exhaust (Why NOT to do it) | Mazdatrix

 

S4 and S5 side housings (irons) are different, but they are the same in the ways that matter to you - especially if you're keeping it BNR (fairly tame turbo). the bottomline is that you can use them with your proposed setup. naturally the T2 manifolds you mentioned that you're getting will bolt up just fine since that's the configuration they were built for.

if they are in good condition, jump on them! as you have described, you have been experiencing what i have - which is they are harder and harder to find. get them and take care to build a solid, reliable engine out of them and protect it because remember you are running higher compression plus boost.

on a sidenote, if you think it's hard to find T2 housings, try looking for T2 rotors.