James,
Thanks for a very informative response. Your read my mind. We've indeed been talking to Custom Metalcraft and will ask them for references. I was using 15 bbl x 15 brix = 225, and then multiplying it by 280 btu/brix, to get 63,000 BTU. So 1-2000 btu/hr for the first 48 hrs seems right on the money. The surface area seemed sufficient, but wasn't sure if agitation is needed.
Sorry for the late response, but just discovered that the lead time on stills is 6-9 months from most vendors so been chasing alternatives.