Velcum!
Your going to love the acceleration with 31's! not..
Gearing is going to be a problem if you drive alot off road. Unsure about onroad.
Alot of people have 31's, so it shouldnt be hard to find what someone has done.
My tyres are 33's. But realsize 32 and alot wiser than most. So i have run into other problems scrubbing. Also my sus setup is not really for noobs as i did alot of playing once i got the feel on whats happening to the handling.
Shackle ramble: (not in your post but good to know)
If you've heard of people with shackles. Shackles are not an answer. Yes they will lift the car, but the stock spring or 2" with shackles setup will make it worse than stock. Unless you have longer springs, then you will be able to get better angles out of extended shackles.
I had double size shackles 1 week after i bought Suzy. Good for instant lift, but bad for everything else. I still run them, but my setup is not stock leaf sizing/mounts position..
2" lifted springs alot of people sware by Arb's - OME- Old Man Emu springs as they are softer and flex more than others etc. but more expensive..
Everyone will have their own opinions with tyres. I went the Nankang mud's cheapo way. They do fine for me.