904 with very hard 1-2 shift

I recently got a 66 dart with a 340, 904, and 3.91s. It has a performance build 904. The 1-2 shift is pretty violent. Doesn’t matter if it shifts automatically or if I manually shift it.
I’m wondering if there is something I can do myself to calm it down. I vaguely remember many years ago maybe removing the servo spring in a 727 to get a hard shift ??? Is this a common thing ? It really bangs 2nd gear, no difference 5mph or 40mph. Hoping for an easy fix.
Happy Thanksgiving

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