What sort of work do you want done? There are shops that specialise in dyno and others forced induction and others ... well .. other stuff.
Visit as many as you can, talk to the people there and get some quotes. Also, don't be afraid of your gut feelings - if someone feels dodgey - don't go there.
Some specialise in all things Nissan. And some don't consider anything pre-1992 as 'performace'. I spoke to one nameless workshop about 7MGTE re-building and was met with yawns and disinterest.
Cypher Industries in O'Conner have a good knowledge of ealy Toyotas - most Saturdays the carpark looks more like the local Sprinter club. Probably a good place to start.
Justin
(Zazk - do I get a discount for the plug ... joke!)