http://www.tomatoville.com/showthread.php?t=19937
I think it might help to read the above thread which is all about growing large tomatoes. Near the end lubadub appears, and he's Marvin Meissner who wrote the book on how to grow large tomatoes.
Seamfaster also has a website you might ask him about, again, in terms of possible seeds for growing large tomatoes. And there are other sources also noted in that thread.
As I'm sure you know the world record is 7# 12 oz, grown by Gordon Graham of Edmond OK, and he did absolutely nothing special at all. That plant was growing just sprawled inground, and in the weeds when he found that big one.
I grow tomatoes for taste and could care less how big they are. But I do understand the challenge of growing for competitions for almost anything, be it parsnips, leeks, cabbage, pumpkins, etc. Same thing here in NYS in terms of how many of the tallest Adirondack Mts have been scaled by a single person. It's the pursuit, the challenge that's of primary importance to some folks.
As for me, I'm content to sit and watch the tomato blossoms open.
