First of all I think that you being new to all this Dillon stuff you do not have a good base to judge whether that deal was a good deal .
I think that you should have listened to the many folks that told you to buy a 550 . That is most likely what your range buddy is doing right now .
Since I have got that of my chest - Dillon will treat you well no matter what ! If you ship your press back to Dillon be prepared to inhale twice when you find out the shipping charge .
Your best bet might be get with somebody else -not the seller - that knows what he is doing and find out what you need to make that into a regular 550 . When you said you have rusted parts on your press - I have my 550 since July 1989 and there is ZERO rust .
Sometimes we made a good deal and sometimes - well - .
Like so many other people told you - Dillon will treat you well they just might have had a very busy time that day .
I am sure that eventually you will be a very happy customer .