Have a few questions-planned stance-wheels/tires

[cjohnson6772]

I'm looking for some experienced input before I dive into a revamp of my front end. 72 swb. I am running 275/60-15 tires and American racing 200s (butterflys)15×8.5 all around. Unsure of backspacing. Anyone know what backspacing this wheel would have came with?

Wanting to add 2.5" drop spindles. Will this combo likely be ok or require a arm trimming? Should I be concerned about tire rub with stock springs?

Also I've noticed a noticeable increase in bump steer and overall unpleasant handling since my LS swap. I suspect moving weight around is the culprit. My mechanic suggested more NEGATIVE caster but I think he is incorrect. I believe it needs more POSITIVE caster. Input?