Changing Lob Storage parms

I have a question about changing Lob Storage paramters. I am running Oracle Standard 8.1.7. and I have a Lob Segment that was orginally set at 50 for PCT_INCREASE. The particular Log Sement currently has 28 extents and has a Next Extent value of over 2.5 gb. The Intial Extent is 40960. Instead of having to add 2.5 to 3.0 gb to the Tablespace to accomodate the next extent, I would like to change the PCT_INCREASE to 0 and the Next Extent to appox 330 MB.
What I am not sure of is that since a 0 PCT_INCREASE means that all extents after the first are the same size, and it had been using the 50% increase, what would all of the future extents be...the value that I want to set the next extent at ( 330 MB)? Also, will this cause any type of issue within the database , since the orginal 28 extents are different sizes and now i want to go to a uniform next extent size? Can I just change this on the fly? This is for a production system and I have no way of testing. Any thoughts?
Thanks in advance.