Do you have the heim joints on the four link arms? These allow you to center the axle and set the pinion angle at ride height.
The goal is to get your body centered to the frame and get the fender lips at reasonably the same height front left to right and rear left to right. Then you want to get the rear axle centered to the rear fender lips. With the centering process, (with an axle with heim joints), the pinion angle needs to be set at ride height and the axle at the correct wheel base and centered left to right. Then you can adjust the heim joints so they so they bolt up.
With your body on was the body centered to the frame front and rear, (fender lips to the frame). It is normal for them to be off a little. The originals were off but you want to get it as close as possible. If you look at the lower edge between the wheel wells with the body on you have a little play to move the body before it hits the sides of the frame. If the front is considerably off you may want to cut the front support off that mounts to the front of the hood opening. I cut the welds, centered the body, and made sure the lips were level with the frame and then rewelded it.
It is very hard to measure the wheel base accuratly from the spindles. Notice the bar that is clamped to the K member below. The center of the K member is the center of your spindles. Hold you tape over the bar equal to 1/2 the thicknes of the K member and then measure back 90" for the center of the axles to see where you are. There is a machined edge you may want to measure to after doing the math deductions. It's easier to measure to than trying the eyeball the center of the axle flange. Also in my gallery is a picture of my four link with heim joints.
When I did all this on mine I started with leveling the frame front to back and side to side with blocks and shims. It is sad to see a car that a guy has put a lot of money into and body or axle is cocked on the frame. Call me and we can discuss it in far more detail.
Wayne
