Limit Holdem blind defense v. shortstack

[luvrhino]

At the time of this hand below there were 20 left out of 27 and only the top 3 paid. The table had been tighter than normal, but still too loose for a Limit tourney. My image, had they been paying attention, was very tight.

In three consecutive rounds (all at Level IV 100/200), the action was folded to the Small Blind:

Round 1: SB open-raised with 1100 chips, I called. He led at a Ten-Hi rainbow flop and folded to my raise.

Round 2: SB open-folds with only 450 chips.

Round 3:

PokerStars Limit Hold'em Tourney, Big Blind t100 (6 handed) internettexasholdem.com

saw flop|<font color="#C00000">saw showdown</font>

Button (t5160)
SB (t500)
Hero (t1715)
UTG (t1095)
MP (t645)
CO (t1585)

Preflop: Hero is BB with J[img]/images/graemlins/diamond.gif[/img], 7[img]/images/graemlins/club.gif[/img].
<font color="#666666">4 folds</font>, <font color="#CC3333">SB raises</font>, Hero calls.

Flop: (4 SB, t400) 3[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/club.gif[/img], 2[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">SB bets</font>, Hero folds.

Final Pot: 2.5 BB (t500)

Results:
No showdown. SB wins 2.50 BB (t500).

I figured he'd open-raise with Top 80%, though any 2 wouldn't surprise me. I folded since I'd only be getting 7:3 with jack-high.

Assuming he'd open-raise with any 2 cards and never fold, i call pre-flop, and the Flop comes K32r, my two questions are:

1) How good of a hand do i need to call him down if he starts with 5 Big Blinds (as above)?

I would have with Q8o...maybe even JTo.

2) Assuming i have J7o as above, how few chips would the SB need to have for my calling down to be correct? If he open-raised with 4xBB (giving me 3:1 odds), i'm not folding once i call pre-flop.

I guess this is largely a PokerStove question. So, after just now realizing that it was free (gah!), i downloaded and, assuming i used it properly, determined that J7o wins 35% vs. a random hand...or a Top 80% hand for that matter. My guess was 1-in-3, so i'm still happy with my fold.

Note that i do consider myself to be a very good limit holdem tournament player and therefore try to avoid marginally chip-EV+ situations early in tournaments. My trouble is knowing how big of a margin i should give up.