BillyDon,
Though you've already mentioned that you'd prefer to not go via an adapter, back around 2014 I went thru a similar issue as you, when I changed rear end gears, etc. Using a GPS speedometer ap, I was traveling about 20% faster than what my truck's speedometer was saying. I contacted Performance Automotive and Transmission Center in Bossier City, LA who said I needed a 20 speed up ratio adapter. Got it and installed it where the speedometer cable connects to the tranny and never looked back. Just something to consider.

Craig

My '50 Chevy 3100 5 window, '62-235cu, 3:55 rear
My truck ....... Respect The Rust
If I'm not working on my truck, '65 m00stang or VW camper, I'm fishing with the wife or smoking Salmon.