for drifting eventualy you are going to need the turbo.
at first simple n/a stuffs should be ok but when you start getting into higher speeds the boost is gonna com in handy
i suggest you try and find a low milage turbo motor
of the same generation(trust me you dont want to mess with a 91 in your car)
just in the future the n/a motor is not gonna have the same power as the n/a will and remeber the rotarys have shite torque so the turbo will come in handy whe needing torque
and if you are going to port your motor do it later like around the time your seals are going to start wearing out why waste money are a perfectly good motor and have to rebulid it unless you really have to....
use this time as a time to learn the physics of the car....the fc3s is one of the harder cars to drift its not as predictable as the s13 or s14 or ae86 from what i undestand