Amazon in the UK have 6400's, ebay may be a goer as well. Your plants will doubtlessly grow under the 'red spectrum' bulbs you have, but not as effectively as they would under 'blue'. It's not a lot of wattage to flower with, so bulbs positioned around the plants and only and inch or so away. Mixing the specrum is also supposed to be good. Mostly blue to veg, mostly red to flower.
Good luck.
JM