3DOF- Plans? where to start

I've visited many forums and make sites on stewart platforms but haven't found anything that is well documented. Any help in pointing me to a few links that have great BOM lists and step by step would be appreciated.

My needs:
I'm building a simulator to work with a roller coaster VR experience. The "chair" will actually be a mock coaster car mounted onto the platform. The entire weight capacity including (1) rider up to 250lbs is about 1200lbs. (approx 1000lbs for the cart if needed)

What I don't know is what servos (no pneumatics at this time) or how to determine the weight/torque capacity each servo needs to carry the load.
I dont want something that will push high and wide. More like a 4x4 suspension on a mild offroad experience.

Also need advice on the rocker arms, what types or brand names.

Ebay links for parts would be great!

Mingra, you might try this site: http://bffsimulation.com/index.php

I have been looking over his plans for a force feedback yoke. I don't know anything about his platforms, but the drawings for the Yoke are quite detailed and easy to read. My problem is sourcing the metric-sized pulleys here in the U.S.

R/Len