People always buy huge wheels and then try to make them work. Buy wheels last. Lower the car and get it working with 15X7's before putting 20" wheels on.
Stiffer springs are $60/pair. I would recommend Moog 5660's. 4" Cutoff wheels are $10 with coupon at Harbor Freight. Crack open the front end, install the new springs, bolt it back together, drive it around the block, measure the height, crack it back open.
Use the cut off wheel to take off 90 degrees of spring and repeat until its about 1" higher than as low as you want to go. (if it is at the perfect ride height or lower, pull the springs out, put the springs on craigslist for $30 as "3.5" lowering springs" and buy another set and start over)
Use a pickle fork and 4lb sledge because you are going to throw the balljoints away after you get the ride height set.
For less that $100 you have your ride height, then take it back apart, add new tall ball joints, new shocks, new bushings, ZQ8 bump stops, etc and get it aligned, THEN think about buying big wheels and tires for it.