See also: Interactive Caliber Conversion application!
I should note that this is mostly taken from the back of Dillon's 650 manual. I'm reproducing it here because Dillon's manual doesn't present it in a convenient table format, and I personally find this a lot easier to navigate and cross-compare for parts I already have. This is just for the calibers which I either own conversion kits for or plan to get; I don't feel a desire to transcribe the whole caliber conversion chart.
Other than jotting down notes on undocumented conversions I pick up along the way, I probably won't need to add anything to this page much going forward. The Interactive Caliber Conversion application now handles all the documented conversions for the 650, plus the 550, 1050, and Square Deal B as well, and it can do pretty, custom color-coded conversion charts too.
Calibers which aren't provided in the Dillon manual will have their names bolded.
Bear in mind that this is ONLY a quick reference, not a replacement for the Dillon manual! You should double check the Dillon manual to ensure that my table here is correct before you go spending money or swapping parts!
When in doubt, refer to the ACTUAL Dillon manual. The Dillon Precision website provides a PDF of the owner's manual free to download. However, it's a fairly slow download at 50MB. I have, for my own convenience, taken the three pages of caliber conversions and printed them to PDF, and Dillon was gracious enough to allow me to make those three pages available to you.