Right, it's not teeming down and there's daylight. Checking has also clarified what needs to be done. (I looked into this years ago and its been a while since I revisited it)
On the type 3 1 litre sierra (and I believe the Maruti is the same) two of the holes that connect the pedal box to the firewall match the 1.3 sierra/vitara booster pattern. (the bottom two) In order to fit a booster, you need to drill the upper holes to match the square 1.3 booster pattern (its square) and enlarge the hole through the firewall. You then need to drill the studs out on the 1.0 pedal box and drill the pedal box mounting flange to suit the booster pattern and (maybe) adjust the pushrod mounting position on the pedal to suit. Alternatively, you could bolt in a 1.3 pedal box and the pushrod should work. The booster has studs on it to retain the pedal box.
Type 3 1.0
1.3
The bottom two holes you can see are in the same spot and are also in the same spot relative to the steering column bolts. This isn't the case with the earlier 1.0 litres.
Note, you may need to move the heater tap as it will be too close to the booster.
As I mentioned the booster pattern is the same between sierra and vitara. This means you can use the 2.0 vitara booster which is larger than the 1.3 sierra booster and will provide a lighter pedal, if that's what you're into. Team that with 1.6 estate vitara ventilated rotors and calipers you'll have excellent brakes.