The type of servo you choose will not affect if the linkages bind up.
The steering mechanism is fully ball-raced so should run perfectly free when built correctly.
Spend some time on in - process of elimination to find out what is binding, check the link rod slides freely accross the chassis and that the hubs turn freely.
There are a few post in threads here with different install pics, have a look. Most folk use low profile servos, however if you run a small ESC like the Tekin (or maybe a brushed warrior!) it will fit on top of the servo.
Ellis Stafford's is below, a good way to fit a large ESC in.
