How do you construct a large retaining wall?

I have a driveway that is supported by railroad ties that over time have shifted and caused the driveway to crack and shift ( A LOT ).. Back of driveway is a 8ft drop off straight down to back yard. I have to build a 8-9ft high by about 35ft long retaining wall. The top of the wall would be the end of the driveway where I will have to re pour concrete or ashphault. Is versa lok suitable for something like this? Should I remove the existing concrete before I build the wall and start from scratch or just build up around it and fill in? Any suggestions would be greatly appreciated