yea revheads right, what ever emissions gear is on the motor has to stay. when i done the ca into 1200 conversion i had to keep the ecu cat converter charcoal canister blah blah but when i put the 12a rotor in it was an early model 12a which didn't need anything
 
is there any chance you could stick with a g13b head just to get it engineered? i think that would make it alot easier on yourself

Ah, I'll just resort to an aftermarket ECU. I've been looking at the Link or Haltech. From the info I've managed to obtain, I'd need to get an emissions test anyway, so I may as well turbo it, get it engineered how I want it. Apparently the ECU needs to be locked (password locked) to be engineerable.

Here's a cheeky tip. Get a massive standard ecu, gut it and put your own aftermarket unit inside it. You might get lucky if you can tune it well enough to pass the emissions test.

You might as well then use a g13a block with g13b gti crank, rods and g16b pistons.
You then shouldnt have to run a catalic converter at least just carbon canister with
1987 vitara g16b computer modified for the turbo. I remember there used to be a cut off 
year for the pre 1969 cars in terms of emissions but not sure if thats changed.
 
The engine block determines the emissions I would have thought not the head?

Booyar, Another possible choice you can consider is errr a rotary but not a normal 13b
eg, I bought a single rotor 13b setup that ran as a Peripheral Ported Turbo in U2ltrs class. 
Being halve a 1300cc or 650cc and times 2.5 gives 1625cc, yet not sure on capacity limits. 
As a PP it made 320hp with the Peripheral port while with extended port plates it would make 
close to 260hp using a disco potato as the 13b flows out as much exhaust as a 4+  litre engine.
Rotor 650cc = 2ltrs cylinder pulses. R5 plates will pass emissions as they pass as an Rx4 engine.
 
I weighed the single rotor components versus an A series main base and came up with this
 
A15 engine block 35kg
A15 crankshaft  13kg
A15 rods & pistons 4kg
A15 head 9.5kg
A15 camshaft, lifters and pushrods 2Kg
Timing chain, oil pump and sprockets 6kg 
total---- 
70kg 
 
650B
R5 rear plate 14.5kg
R5 front plate 11kg
modded E shaft 5kg
S5 rotor 5kg
Timing case 3kg
oil pump & Timing parts 6kg
total-----
45kg
 
G13bb is about 15kgs lighter than A15 or 55kgs
 
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Sorry for the extra post, the work computer froze up on me.

One of the first people to experiemtn with the single 13b passed away recently his name was Leon Prommett he used it in his daily Rx7 s2 or s1 and darted through sydney streets were many would spot him. It was extend ported with a downdraft 45mm twin IDA weber and supposedly made 120hp to 130hp at the engine at 8500rpm and he said the torque was equal to a 12a orignal engine and the single 2.5 inch pipe mady it revvier. He said he was thinking of turboing it but was happy with the 70% improved fuel consumption and simplicity of it. It pulled the 1200kg rx7 quite well and was fun to drive.
Simple cheap economical and 120-130hp doesnt sound like a rotary engine
 
Initially the cost of modifying an e-shaft and rear bearing is around 800-1000 dollars but after that uses halve the part of a rotary which is mainly seals not to mention the easiest exhaust system youve ever come across equal to a lawnmower 
 
Its not for everyone but I have one just in case I change my mind as the S1 and S2 gearboxes are still easily available and they  weigh around 25kg which is perfect for the overall weigh conscious performance upgrade. 
 
To make 120-130hp from an A15 you either have to turbo it or spend big money for tuning it right.  I see it this way for 130hp from an A15 turbo or NA should cost around 3-4000 dollars then you have to spend big to get the right gearing for your gearbox or a good gearbox itself which is not cheap as you need closer ratios for the more powerful A series, turbo would be better but the your a15 will be 50kg heavier than the 650BEP in the end. 
 
Sorted A series w/ 5 speed around 5000  - VERSUS -  Sorted 13b%2 w good rx7 s1-s3 box around 4000  
 
If you get anal and want further weight reduction on the rotary eg. alloy endplates then you aim for some of the Kiwi, American and Ozzie billet plates coming out for around 50% weight reduction. eg. rear end plate 14.5kg standard iron down to 7kg in cast alloy with plasma coating and 6kg (11kg stock) for the front one.  from 45kg cast base 650B does down to 35kg which is not that bad but cost is 3500aud for 10kg!!!!  Yet the weight would be like a motorbike engine but much simpler to rebuild or tune.  35kg base + 25kg gbox + 10kg manifold/carbs = 70kg vs a15 + 28 kg box @ 125kg - 55kg difference. 625kg b10 - 55kg = 570kg add billet coil overs for the front no leafspring -10kg, bumperettes -8kg, lithium battery -8kg,  (still 3rd price of a simlar weight Lotus 7 replica but sheltered from the elements!)