You have lotus and two moxen alone - why run tinker??? If your proxies plan to be power, then why not run BSC and just win rather than use leveler? Sol ring is fairly cheap and a must have in that deck.
Leveler is there to win via Lab maniac.
SB is meta dependant but you can start with
4x Steel sabotage
1x hurkyl's recall
1x echoing truth
2x nihil spellbomb
3x yilid jailers
2x trickbind
2x pithing needle
as far as a back-up plan, you could always just beat-down with your creatures + timewalk. A single Jace, the mindsculptor would be good here as your back-up as well as Blightsteel colossus if you add in more mox/sol ring/mana crypt.
Also, I would just take out the tinker, 1x street wraith and 1x counterspell and add 1x Flusterstorm, 1x tendrils of agony and 1x Doomsday if you plan on sticking to the combo plan.
you can also check out Steve's Meandeck Doomsday Laboratory Maniac deck for further inspiration if you go all-in combo:
http://www.themanadrain.com/index.php?topic=43240.0hope this helps
