SWAT- I think that you should shoot for how much horsepower you want, then decide on a boost level. Different horsepower levels will require different amounts of boost. On 10-12 psi, with a WELL tuned engine, like one with a TEC-II, you could probably shoot for something around 280-300 @ the wheels. I *think Shiv made 292 @ the wheels @11 psi, on stock internals.
If you really want to be able to drive the car and not baby your tranny all the time, then yes you will need to upgrade to a dog box or synchro mesh gears, which are just basically hardened gears with a lot of the same feel as stock.
The cluctch will definetly be of concern at high HP/Torque levels. You have several options, including ACT and Clutchmasters, both of which would probably be fine for what you are looking for.
Graham