Michael
My lathe sits on a table that was made from the base from an old gas grill - four legs, with wheels on two legs so that I can (in theory) lift one end and roll it around.
The top of the table was made from 2x6's edge jointed with biscuits and glued to form a solid top. I then put short lengths of 2x4s across the 2x6's at the point where the the top would attach to the legs. They serve two purposes - the reinforce the top to assure that the 2x6's never separate, and also provide an additional 1.5" lift at the legs. Then, I put two additional 2x4's on top of the 2x6's directly underneath the 'feet' of the lathe to provide additional height. And everything is firmly bolted together so that everything moves together. The result is that the axis is of the lathe is close (enough) to my elbow height for comfort. It's still a bit wobbly (the grill base was designed to carry weight, but doesn't have a lot of lateral rigidity), but that's only an issue if I'm turning an unbalanced piece.
Are you getting the stand shown in the picture with your lathe? I presume that you are a 'tall dude' and are concerned that the standard height is too low. My suggestions would be to consider a couple of things:
1. Is it possible to use longer bolts at the point where the bedways attach to the legs? If so, could you insert risers at that point? I'm thinking one (and perhaps two) thicknesses of 2x6 for an increase in elevation of 1.5 or 3". That would be pretty secure/rigid.
2. You could also construct risers from one (or two) thicknesses of 2x6 lumber that fit under the feet of the lathe. I presume you could run some carriage bolts through the feet to keep the risers in place. I would run them front-to-back rather than side-to-side so that you don't have something that your feet would bump into under the lathe. The one concern with putting wood risers in at that point is that wood on concrete is a bad combination, so if you are going to be putting the lathe on a concrete floor, I would think you would want to use treated lumber to construct those risers.
3. If necessary, you could use a combination of these two approaches for a total increase in elevation of as much as 6".
The limit would be that if you add too much height, you could end up with a 'top-heavy' arrangement that could be a bit 'tippy' in the event of a catch or if you are turning a piece that isn't balanced. For that reason, you probably don't want to add any more incremental elevation that is necessary. Also, this model is 3/4hp - more horsepower means more torque which aggravates this problem.
If tippiness is a concern, another thing to consider is putting a shelf on those brackets on the leg, and laying in some weight - a couple of bags of ready-mix would add a lot of stability and make up for any tippiness that the additional height might create.