Making your own rear Shock brackets?

We just got the rear end in where we think we can live with it. The motor is at about 3 degrees down and the pinion is up at 3 degrees. Now we are trying to figure the best way to install shock. Does anyone have any specifics that I should keep in mind?
I know that they should have 25-30 degree lean to it but does the brackets matter if they are on the same side of the axle?
Plus how do you determine whats the right heigths.

I appreciate all the help you guys give it has saved me already.

Thanks

Go to the boneyard and choose any full-sized car with leaf springs. Remove and purchase one of the shocks and both spring pads where the shocks mount. Modify the pads if you have to to fit the old Chevy and bolt 'em in. Fully extend your donor shock and measure the center to center distance. Now fully compress the shock and measure the center to center distance. Adding these 2 distances together and dividing by 2 will give you the installed length of that shock. If the shocks mounted behind the diff housing on your donor vehicle, place a brick behind each rear tire and use the bricks to hold a string in place. Run the string from the left rear brick over to the right side at the center of the shock mount at the spring. Now raise the string up, keeping it taut, to a point that equals the installed height of your shock. That will be the centerline point for your upper shock mount. Now repeat for the other side.

If the shocks mounted forward of the housing, put the bricks in front of the tires.

When you have the mounts fabricated, go down to NAPA and get a set of shocks made to fit your donor car and you're good to go. :)

P.S. I guess it goes without saying, but I'll say it anyway, the car needs to be at ride height sitting on the tires to do this properly.

Ok just a couple of questions, the donor car was a mercury Monarch and we used the 8 inch out of it. we got the bottom spring plate as well we are planning on using them. On this car the brackets put one shock in the rear and one shock in the front.
I dont mind doing this but is it necassary or could you run them both on one side that would keep us from making two diffrent upper shock bars running across the frame.

Also we dont have the body on the frame and we have donor wheels and tires on the car. Will this affect ride heighth? I feel that it will. but will it get us close?

One last thing with the bricks either in front or the rear of the tire, do you hold the string in the center of the brick or ?, that part I just didnt understand where to hold the string. The rest of it makes perfect since and I appreciate all the help.

Thanks in advance

It doesn't matter where the brick is, as long as you have enough room to clear the diff housing with the string. If you held the string with the bottom of the tire, you wouldn't be able to swing the string up straight across the car because of the housing in the way, that's all.

Yeah, you definitely want the car at ride height so that you get the proper compression and extension on the shocks when it's finally goin' down the road. What you can do is approximate the position of the upper mount and make several different mounting positions so that you can use the one that is closest to being right when you have the car together.