I was playing around with trying to convert scale feet to full size inches using Microsoft Excel to speed things up and this was the syntax I came up with(placed in cell B1) =A1x12/29. Cell A1 would be you measurment in scale feet. Am I correct that you must take you scale feet measurment, multiply by 12 to get scale inches and divide by 29 (or what ever scale your modeling in)?
That should do it!