Hmm ... if your timing is right you could grow Dwarf Namwa to fruiting size and then send it outside to fruit for 5-8 months.
Nice going on the conservatory, an 11' x 11' translucent roof is excellent.
PAR by itself is a poor measure, because ultimately it is the spectral distribution that is important.
For optimal performance from most budding and fruiting plants, what you want is 1200 Watts of net output directed at each 1 square meter of plant surfaces from a distance of 1 meter, AND with a color temperature of 6500 Kelvin (CIE D65):
Commercially, the 6500K high output fluorescents are the closest to this. In contrast, check out the distribution of a standard HPS lamp:
