Should I go with mild steel or chromoly. I figured the mild steel would be stronger but I'm not 100% sure. If the chromoly is as strong or stronger I'll go that way for wieght reduction.

 

I would go with chromoly. It's lighter and should be stronger than mild steel. It will flex more, and will tend to bend rather than break like steel does.

 

I've been trying to figure this one out as well (check my poll/thread in the Handling section). I think I've finally made the decision to go with a regular mild steel and pick up Madman's motor plate. Mainly, due to the his suggestion of using a k-member with no motor mounts to allow for more header clearance. Granted it will add a bit in terms of money, but the added benefit of more space and strength of the plate setup will hopefully be the best of both worlds.