Obviously, there's a limit to the weight your players can be in a tournament (4 grams I think?), but if you're making your own house rules, why bother with weight limits, right?
If there's no limitation being set, and you could give any players any weight, what would you recommend is perfect for lineman, ends and backs/backers, and speed guys? Would you set them all the same weight (assuming you're using Power/Strength/Fast bases from ITZ), or would you make the line the heaviest ones and receivers lightest?