Hi, i've also got a slowtrak, as far as i am aware you can not buy a lift kit off the shelf. Which is pain in the a** to say the least.
As for 4trak springs again i can't say if it will fit or what sort of lift it will give.
As far as i know the majority of lifted sportraks go either with a body lift, which means lifting the body off the chassis and fitting spacers in between.
Or a suspension lift, where by with the rear you fit extended shackles to the leaf spring, extending the shackles by say 4 inches will lift the back 2 inches. With the front you simply adjust the torsion bar to match the height of the back.
On a standard sportrak i would not advise going any higher than 2 inches as this will put strain on other areas.
A good place to find out in more detail would be
www.daihatsu-drivers.com Just type sportrak lift into the search bar.
I hope this is of some help to you,
Cheers Phil