Wow! Usually posts this old and answered late {or never} equals an original poster that never ever comes back.
I've got a Manco Dingo in the garage with
springer spindles and I think the only angle in them is fore and aft, to provide a bit of caster.
I'll check later.
Also, I'd go ahead and get a complete, pre-fabricated spring spindle and bracket set and not try to cut, weld or modify your current setup. Luckily, they're a Manco part and still made.
I'd check into some bouncy, balloon style ATV tires. Too bad they don't make these tires anymore; more tire than wheel: