Watch out with inductor replacement. They will likely have a different DCR which can have a negative affect. Stick to caps and resistors. A good mid budget upgrade might use Mills resistors and Sonicaps. It's always a little tough to find exact cap values. Crossovers aren't that complex and don't require a PC board. You can point to point wire them on a piece of nice wood. Glue or wire tie the caps down with a deflex pad under them. Good luck.
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