Bringing that pair of EPI 100's back to factory norm would a major judgement call due to cost.
Today I installed some new, currently in production, up to date tweeters in some Polk Monitor 5B's. Cost was about $165CAD. Add to that, $15CAD for new grill pegs, $70CAD for new film capacitors, $40CAD for new wire wound resistors, $85CAD for one parted out woofer of the correct type and I'm into these speakers for $375,
I am not including the original purchase price as it was $2 at a garage sale last year.
If I were to re-sell, it was a very bad investment because I doubt they would fetch anywhere near what I spent on them. But, my intent is to keep them as they will likely be my only pair of speakers fairly soon.
I can understand why someone would re-purpose and modify boxes on hand for use with different drivers. I did that myself when I loaded some E/V drivers into some DIY cabs that I bought because I liked their look. The Sansui and Philips drivers that were inside, went elswhere.
Maybe those modified EPI boxes and the drivers inside will sound quite satisfying? Maybe more satisfying than factory stock EPI 100's?