Help on model a front end set up

My whippet has a Model A front end (axle assy) on it and I will be making some changes to it soon. Question is, Does the straight axle have a recommended angle at installation? That is to say, if you are standing at one wheel looking across at the other side. Should the Kingpins be straight up and down or canted forward or aft ? Why I am asking is that I want to replace the split wishbones and attach brackets to the frame. If I lengthen the attach brackets and drop the attach point down a bit, will it change the axle angle?

 

7 degrees positive caster....or thereabouts w/o binding spring

 

Yes, lowering the mounting points will increase the caster, and vice versa. As the above poster said, 7 degrees is optimum. The spring mount should be at the same angle so the bushes dont get slogged out.