Here is an Excel I made for the Big 21. If this works and you can open it, enter your target weight for each lift in the yellow box. Most of the formulas work by subtracting from the target weight. Also, the whole thing assumes gradations of 2.5kgs, not 5lbs. I think that might be pretty important.
If this attachment business doesn't work but you would still like a copy, e-mail:
jwluckettiii <AT> yahoo.co.jp.
Careful there. That's Japan's yahoo, not DOT COM.
And finally, if anyone notices any errors in the thing, please let me know.
OK, here we go...