In stock form, the Tj/Yj/Zj all have the same width axles. If he narrowed the D60 to keep the stock track width, your in good shape.
I would find out what differential it has (powrlok, traklok, posilok all mentioned) as that and the gears and labor will determine a lot of what it's worth.
The bracket kit runs $200-$300, and the gears are around $250 including install kit. Then labor to narrow and cost of custom axleshafts. Add the cost of the differential and labor to install all of above, and $750 isn't sounding too bad now.