Thanks for the comments. Much appreciated.
I plan to start with the IX Corps landings in the south since I have the best documentation for that.
I found a detailed report from the 81st ID on their plans for Olympic at the CARL. This link for IX Corps:
https://www.alternatewars.com/WW2/Downfa..._Corps.htm
This link for the 98th ID.
https://www.alternatewars.com/WW2/Downfa.../98_ID.htm
Maybe I'll take a second pass to see what I can dig up on the 40th ID, and that RCT were up to off shore.
Also dug up the naval gunfire support plan. So I have had a lovely day sorting through the older BB's, CA's, and CL's. No fast BB's or Baltimore CA's for the fire support groups. Next up, the DD's and assorted LCI's and LSM®.