welding perches/setting pinion angle

[88dragtop]

I picked up a 9" rear for my 65 but have to weld on perches since it was modified for a 40 ford. Should I bolt it in place, tack weld perches and then drop and finish? What's the angle or should I just measure the existing 8" angle and put the 9" at the same?

 

[brianj5600]

If it is a driver you would be fine copying the 8". I it will be making good power and using sticky tires you will want the pinion down 2-5* compared to the trans.