Based on widget's insight you'll be using the 075
So now you need to install the new capacitors you bought in place of the old ones
i suggest you get yourself very small cone speakers like 1-2" dia. max that will go above 7khz, this to avoid using the 075 at this point with such old gear in case of malfunction that may damage the 075. These speakers can be found at electronic surplus stores for cheap.
Test the crossovers and L-pad using the small speakers with low level music. Exercise the rotary L-Pad controls to confirm they work ok
If testing seems to go well then you're ready for the next step with the 075 diaphragms, and hope for the best