First of all, if there's a website or a faq that covers this, please reply with the link (saves yall some time ;) )

Here's the question.
We all know how weak the first run b230ft's are (for performace at least), so after turboing my na 740 (b230f), the two things that linger in the back of my mind every time i romp down on it are a) will a rod break this time, and b) will i burn a valve. Granted, of the two, i'd much rather b happen, cause i have a pair of turbo heads at my disposal, they just need to be sent down to the local head shop for a fix up ;).
I've also turned the boost up on my new 760, (b230ft, no k), same rod fears are also in the back of my mind.
I'm getting to the point, i promise

At a recent trip to the local boneyard, I discovered several late 70's early 80's 240s, most with engine/transmission still in them (no turbo cars)
But its my understanding that the na b21's and b23's are still stouter than the b230's, with a bigger/better/stouter crank set up. For my purposes, the b21's are a shade small (yea, i could get em bored, but thats extra $$) but the b23's might work.
So, the question is, what are the sizes of the rods in the b21s and b23s, what problems might i encounter (other than the feed and return lines) were i to out fit a b23 bottom end with a turbo head (and in the case of the 760, turbo pistons) and would it be worth it?
I've been trying to track down a nice 93+ 940 engine, but at the moment they're out of my price range.
Thanks yall!