The whole head of the machine (motor, spindle, and all) goes up and down on the column. Too little clearance can be a problem, much too never is. Your block could be anything from paper thin to 6 or 7 inches (depending on your vice or clamping kit). By the way, the chuck isn't used when milling, it can't hold endmills tightly enough. You'll need to get a set of MT2 collets to hold your endmills.
Bang for the buck, I'd go with it's
bigger brother (in fact I plan to get one once I solve my cash-flow problems). Bigger motor, bigger table, R8 spindle taper (better availability of collet and endmill-holders), doesn't have the drillpress-style extensible quill (makes the head more rigid, better accuracy).
But, yeah, the little one will work okay.
Oh, and LittleMachineShop isn't great for tooling, but they have replacement parts for every bit of both machines, plus some good hints and pointers.