The best you can expect to do with a NON gas-checked bullet is about 1,400-1,500fps. You can go upwards of 2,200fps and still get accuracy with a gas-checked bullet from the '06.
My preferred powder for the '06 with cast bullets is #2400. I start at 20gr and work up to around 25.0gr. Where-ever accuracy starts to drop off, or where it shoots POI/POA at ~50yds.
Be really careful to avoid double charges by using loading blocks and double/tripple checking powder levels with a pen-light flashlight.
One over charge can ruin your day and rifle...
Up to ~15.0gr of Unique, or the mentioned 13.0gr of RedDot will work with the non-gaschecked bullets, but are really just short range plinking loads.
With some judicious loading, you can get good accuracy with H4895 up to the ~2,200fps level. Ditto the IMR4064, but don't exceed ~42.0gr or you'll get terrible leading and accuracy.
SR4759 and XMP5744 are also superlative "cast bullet" powders. But NOT IMR4756, A PISTOL POWDER....