I ordered some cheap crossovers from Amazon. (I didn't have any laying around.)
https://www.amazon.com/gp/product/B002RE9P0I/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
They weren't allowing the 6.5" speakers anything more than the highest frequencies, so I bypassed the crossovers for the 6.5" speakers. I have some bass blockers that cut off below 150 hz laying around, but I haven't attempted to use them yet.
This is a total "seat of the pants" project and not anything that was rigorously researched. I honestly expected to toss them in a garage sale and have been pleasantly surprised with the outcome.