If using the same bullet from the same manufacture, only difference being that it is a flat base vs. boat tail (or vise versa) is the data interchangeable? Reason I ask is that I found a great load for 150gn boat tails in my rifle, but all I have on hand right now are flat base. Thanks!

As long as you are in the range recommended in the reloading manual(s) you should be safe. Performance is another matter though and you'll have to find out for yourself.

Your chamber and barrel don't know the diff but when the velocity drops down to the speed of sound, the bullet does. Use the same load data. That is not saying they will be equally as accurate.

Okay thanks. I appreciate the quick feed back.

As long as the COL is the same or close to it, there is no real difference.
Trajectory's will not be the same of course.