If I understood correct
Hi,
You have built a matrix with shift registers. You have not mentioned the column and rows details. I prefer column cathode, driven by 74HC595 boosted through ULN2803 and Rows driven by P-Channel MOSFETS. So if you have the matrix ready. You need two things :
A serial / shiftout to load the column LEDs and a ROW scanner. For me microcontroller is the answer. (I only know and work with PIC).
A second option is to have your parallel port drive it.
Search for LED dot matrix display on this forum you will quite a lot of reference and suggestions.
Best of Luck
Regards
Sougata