ok..Here I go.

Nobody can answer your questions with any certainty without knowing EXACTLY what front struts/calipers/lower arms/castor rods you are using. Even if they do answer it, the suggestions may still be way off. Most of the racing done in 1200s was done in Sedans or Coupes, so they'd only ever be unreliable approximates, especially with the different weight distribution between the models.

For tyre size, the rear is easy. On a lipped guard you can just squeeze 205/60/14 on the rear in a sedan, I expect 215s will fit a Ute. You'll need custom offset wheels to fit this.

Based on my assumption that this is your only form of transport, and you drive quite a bit. Here's a summary of my advice:
1. Get 185/195 size tyres on a 5.5/6 inch rim in a common size.
2. Lowering your car will make almost no difference to handling (if that's all you do)
3. Getting 16+ inch rims will mean you have to fork out $800 every 2 years for tyres, because of the low profile for 1200. The car will also wander all over the road with wide tyres.
4. To flare the guards properly for > 205 tyres, they'll need painting afterwards, if you have special paint, it'll need a whole body respray to paint match.
5. Call Pedders about your spring/shocks/reverse eye requirements. They should be able to talk sense. Do the suspension as a package, and get someone who is REAL, to guarantee that it'll work.
6. Make sure that you get the best shocks that you can afford.
7. Only get the guards "lipped", to preserve the 1200 lines.
8. Don't use lowering blocks for more than 1 inch difference.
9. Using the same size/offset tyres on the front and rear means you can get out of trouble if you get a flat tyre, it also saves on tyres costs, by allowing you to rotate the tyres at least front to back.

I'll be an old man, and also say this:
Suspension upgrades, in conjunction with putting larger tyres on, is a serious undertaking, and those who aim to satisfy "looks" requirements over function, will be driving a different car in less than 12 months due to back pain from poor ride or accident..

Some may say buy some cheap second hand parts, but buying suspension parts from a wreck is risky, as it was most likely the cause of the other guy's crash

Save up $1000, then talk to Pedders.