Suzuki 4x4's are all 5x139.7 PCD (except the really new vehicles which are 5x120, I think). *
Edit - they're 5x114...
The swift is 4x114.3 PCD. So the discs definitely won't fit, they're 4 bolt not 5, and they have the wrong spacing.
The calipers - they won't bolt right up, no. No calipers will bolt right up, you have to
make a bracket for them. Since you're making a braket, you can make it so anything you like fits.
If you
adapt brakets from the front of an SJ to fit the rear, then SJ, Vitara and Jimny front calipers will fit. Whether or not Swift calipers will fit is anyone's guess - although going by what brakes international tells me (250mm disc on the swift, 290mm on the SJ) I'd say they won't just bolt right up. Even if the bolt holes match up, the curvature of the inside edge of the caliper is likely to mean it fouls the disc.
This is hardly proven, though. Your best bet is to pull one of the front wheels off your SJ and see if the swift caliper will bolt up - if yes, use it on the back (although it's 51mm, so if you don't already own one, don't buy it - just buy SJ ones instead so you only need one type of brake pad).
Also be careful - if you put 51mm calipers on the back but your front calipers are girlings, you'll kill yourself. Girlings are 48mm, same as Vitara calipers. You'll end up with stronger brakes on the back, they'll lock up under hard braking and make your SJ go into a spin. Put the larger calipers on the front (ideally you want about 30mm rear with a 48 front, from memory - although that could be wrong, I'd have to do the maths again and I really can't be bothered right now).
Anyhow, all the best mate, and look at brakes international for bits. They've never given me trouble and they're cheap.
Oh, and bigg red. They're good too, just not as cheap.