Hey TenorClef: you've received some good responses thus far. Just to add a little -- often the "casual kilts" have slightly wider pleats than the standard tank. The factors that contribute to the amount of material required are: your measurements (both waist and hip as KiltedKnome noted) and also the size of the set. As others have said, you are probably pretty close to having enough material for a full-blown kilt with standard pleats of 3/4" (+ or -); so look seriously at having a traditional kilt made. You options, if you end up without quite enough fabric are a casual kilt with pleats a little larger ( about 1" or a little more) or alternatively you have more than enough for a box-pleated kilt.

Good luck with your kilt, and let us know what you end up doing.

And of course ....