I have done a ton of those replacements using those body mounts you have there and you have to really line them up and do one at a time.
Draw a center line to the frame from the hold in the rotten mount, then measure to the center from the frame and cut off what you don't need on the replacement pieces (if applicable).
Then cut the old one off and tack in the new one, get measurements, make sure it is good, burn it in.
Or, you can cut off 2, one on the left/right, mount the tub, line up all the other 10 mounts and do the work to the 2 you cut off and you get an exact fit to your tub.
This is lots of extra work, but it will be perfect tub to frame.
Also consider the height of the mounts where they are... you can keep them as is (measure to make sure), or weld them up an inch higher and get a built in body lift without pucks.
cb