so im going to turbo the b20 would it be good to get an ls transmission

 

an ls transmission would bolt up, if that's what you're asking.

but I believe the ls transmission is geared kinda long, so it'd be interesting to drive coupled with a turbo'd motor.

I'd suggest maybe a GSR motor? A b16 transmission would probably be geared too short (cruising in 5th gear, 70 mph, at 4500 rpm (that might be a slight exaggeration lol)? No thanks [8D] )

Or you could get technical... maybe a b16 transmission with gsr 4th and 5th gears?