I would start with 25.1 and see what it does. It would be best if you have a chronograph because you could then compare what velocity you are getting against the book. Also, I normally work on .5 grain increments. To make it easy, in this case, I would have tried 25, 25.5, 26.0 etc. With a chronograph you can quickly see how the powder increase affects the velocity.
Not sure why you are crimping, but if you are, hopefully you have bullets that have a cannelure, or you are using a Lee Factory Crimp Die (with which I have no experience). The only cartridges that I crimp are for tubular magazines (lever actions) or revolver rounds.