Actually for an automatic B series and for a daily driven car with family duties thrown in, my frank advice is steer clear of doing turbo conversions. A properly done one gives you great fun, yes, but also adds to your overall running costs in terms of maintainance and the greater number of wear and tear parts to worry about, not to mention the hassle of dekitting to stock for the annual inspections. Not worth the trouble in my opinion.
For frankenmotors, good upgrades of torque which essentially means for overtaking duties on a day-to-day basis you will never need to 'kui tec' ever again haha...
But all this talk is best kept offline. You never know which kaypoh-kia is trawling the open Forums, if you know what I mean?
Workshop wise, most competent workshops in Singapore and Malaysia can do a good job of what you're after, some cheaper than others some better than others. If you have your regular mechanic, let him do the job. If you have a regular workshop, let them do the job. If you don't have any of the above, but have trusted friends who have had enduring good experiences with their own regular workshops (keyword being ENDURING, no one hit wonders here yah?) listen to their advice and listen to your own impartial mind. Information found on Forums is just that, information, and should always be taken with a large pinch of salt. It is far better to listen to someone you can face to face talk to rather than disembodied voices on a Forum, no matter how 'well known' they might be, right?
And lastly, yes, your autobox CAN take the torque from a mild 20. With your partial R head you already have a good base to start from! Just don't go right foot happy all the time (to ensure your gearbox has a long long life haha), and you'll have alot of fun with the end result, you can bet on that!
...also appreciate if any bro could advice of any good workshop and cost involved to get it done....pm me if confidential or sensitive.... 
...stock b20 u can expect at least engine 200bhp , simple and sweet 