Rear coil over questions

[touring63]

I am looking for some advice on my 63 nova project. The rear is a nine inch with a three link and a watts link. Currently the top shock mount bar is not mounted. I am looking to purchase them now and don't know what I should go with. Is a taller or shorter shock better? What spring rate to go with? I am not sure of the weight currently but I would like a good starting point. The floor will have to be built so I can mount the upper mounts at almost any height. I am thinking some brand of single adjustable coilover maybe ridetech? Or qa1? The car will be just a low, big wheeled, big braked, mean street car no track days planned. Any opinions would be great.
Thanks in advance.

[touring63]

Also they will be mounted about 20 degrees from vertical.

[Musclerodz]

Typical setups manufacturers are using is 5" stroke shocks out back vertical. With 20* tilt, you could stay with a 5" and keep more travel which is always better

[ironworks]

Also they will be mounted about 20 degrees from vertical.

20 degrees is an awful lot. Bring it more upright. 10-11 degrees max

[Musclerodz]

20 degrees is an awful lot. Bring it more upright. 10-11 degrees max

good point.

[touring63]

Thanks for the input guys. I can mount them pretty close to vertical. I geuss in my head I figured mounting the lower mounts the furthest out on the axle would be the best. I could mount the lower mounts inboard of the three link mounts. Do you guys have a good starting point as far as spring rate? I am thinking of going with a ridetech or qa1 that uses a 10 or 12 inch spring.
Thanks again

[marolf101x]

spring rate is difficult to guess. you really need to weigh it and use the spring rate calculator located here:
http://www.ridetech.com/tech/spring-rate-calculator/

However, if it's set up similarly to our 4-link locations you'll likely use somewhere between 175-300# springs.