There's a lot of misconceptions with the geforce and quadro cards, first let me answer the question the GTX 770 will work far better than the k600, I know this from experience as I work with a Geforce card and have used a quadro 4000 with some bad results.
First of all with Maya set to DirectX the Geforce cards work brilliant, there are the occasional bugs however with the correct Geforce card you can get a good level performance for the same price or much less. Firstly I would advise buying the GTX 770 4gb version as if you're using Maya I'm going to assume there's a possibility you will be using either zsculpt or Mudbox to assist the concept sculpts, or texturing etc etc... one of the limitations of the Geforce line is that they don't have the large memory capacity that the Quadro series gets however you do get a large amount of cuda cores at a higher frequency clock speed, which does help for certain operations. Yes the cards are somewhat flawed but put it this way, the GTX 770 works far better than a quadro 4000 in REAL WORLD conditions I can vouch for this, I have modelled and created quiet complex scenes and the card has handled it way better. now this usually down to the Quadro itself, the Quadro 4000 is wayy to old now in comparison to the GTX 770, however the GTX 770 was replacing a 480 the very 480 that replaced the failed Quadro 4000, both of them cards together didnt cost as much as the Quadro 4000.
So if you want to spend less get a decent amount of performance then get the GTX 770 4gb version, just remember make sure the view-port is in Direct X and hide parts of the scene or model you don't need. My method of handling high density meshes and large texture sizes is simple. segment you're model, create multiple uv's for different areas of the body or objects and model in smaller chunks. When it comes to animating if you plan on animating use a low poly substitute then simply switch the model back when you are ready to render or playblast. once you have modelled you're scene and are ready to render the cpu and ram will take the strain of the large scene size so along as the right methods are used you can create models and entire scenes that a thousand pound Quadro would struggle with.
"If you have the chance to buy an expensive Quadro they do make you're life a lot easier, however it depends on you're current job list, or what clients needs are, most don't need em and get sucked into Nvidias marketing hype."