I totally replaced the drivetrain on my 7.5FX. The original chainrings were 26/36/48 and I changed them to more of a "road" triple -- 30/39/52. The cassette was 11-26 9 spd and I changed it to a 12-23 10-speed.
The thing you need to watch out for is the compatibility with your derailleurs and shifters. Regarding the front, the FD will usually be capable of a certain range, you need to make sure that your new chain rings are within that capacity. For the RD, the cage length represents "capacity", so if you make major changes to the chain rings then you might have to change the RD (for example, going from a double to a triple usually means a short cage RD wouldn't work any more. Also, if you have a 7 speed and you want to upgrade to something other than a 7 speed, your shifters may not be compatible (depending on what kind of shifters you have).
All that said, if you keep with a 7 speed and make only the changes to gearing that you suggest above, my guess is that your derailleurs will likely be compatible. The point is that you need to check and be really certain, or you will own some parts that don't work!