thanks for the replies,
according to the datasheet on the 74HC125's they are quad buffers jaycar.com.au/products_uploaded/ZC4842.pdf so i would need two, the circuit is operating at around 10Mhz, only reason i thought the latency would have been an issue is if the lines became un-synchronized.
the LED's from the TLC5940's are driven off of a separate power supply and input pin into the TLC5940's so the buffer is only for the io lines to control the chip.
I tried running the TLC5940's with 3.3 volts, and they seem to be a little unpredictable, i figured this is probably because they are at an indecisive point between whether it is a 1 or a 0, so in increasing the voltage should increase the definition and should in turn fix that issue. (hopefully!).