Furniture and Furnishings - Retro Leather Couch Legs

My husband and I snapped up a couch and loveseat set at a secondhand furniture store yesterday. I wasn't nuts about the legs but the rest of the couch is fabulous--almost perfect leather, buoyant seating, eye-catching design. Upon getting them home and examining the legs, I'm pretty sure they're new additions: the leather is a different grain, the workmanship is shoddy while the rest of the couch is quite good, and the bottom liner of the couch continues underneath the legs. I would like to remove these legs (which are basically wooden boxes nailed to the bottom and covered in leather) and put on something more like these:

8 Tall [COMO-8] - $37.00 : Tablelegsonline.com - 8" cylinder legs. (http://www.tablelegsonline.com/shop/8-tall-p-383.html?cPath=9_15)

The legs would need to be 8" tall (ETA: at least. 9" would probably be best.).

Would something like that support this sofa? Or will I need to find something more like:

Ferrous Hardware - 4" cube legs. (http://www.ferroushardware.com/cart_cat.php?Cat=11&nl=0&oi=0) (might be hard to find something tall enough)

Here is a picture of the sofa. The loveseat is just slightly shorter in length.

http://www.katie-mike.com/leathercouch.JPG

Since the wooden boxes extend the entire depth of the sofa, should I take this as a cue that the legs must be super-supportive? Or will I be okay with just four 8" legs? I don't think the couches are extremely heavy. I only weigh 100lbs and had no problem lifting and dragging them around my living room by myself.

Any advice on replacing sofa legs is very, very welcome!