Popcorn, you're a maniac! I haven't seen someone build a stepped a-arm in a long time. You already know this, but gusset the crap out of it, and box it where ever you can.
If you want to gain a bunch of caster, check out my caster thread, where I devised a very simple way to gain a bunch of caster for essentially no money.
http://67-72chevytrucks.com/vboard/s...d.php?t=501241
I love what you're doing, keep it up. Maximum effect, with high quality work being done on the cheap. You're talking my language!!