Turntables

I would like to build one from scratch but just don't have time to do it. I rthink that I am going to buy the digtal indexed one from Walthers.
 
What size engines do you need to turn? I'm searching for one large enough for 2-6-6-6's (about 130 scale feet) and the Walthers one looks pretty good. Though I'm nowhere near ready to install it.