Sc300's have limits to modifiying the inline 6 cylinder motor and are really not powerful enough to drift in my opinion... The SC300's come in automatic and or manual transmissions, but I would only purchase a manual tranny if you plan to modify... Many people do engine swaps on the sc300's with the Supra 2jz.. motors... The Sc400 have the bigger V8 4.0 liter motors and are capable of handling up to 400-500whp but the SC400's only come equiped with automatic trannies which limits you to modify or drift as well...
I own the Sc400 and love the car but the tranny is a hinderance when modifying...
The SC300's are a bit gutless in stock form, I would look into another car for your interests... Maybe the manual IS300's or something for drifting, something smaller and lighter, that is if you budget permits...I've seen some pretty spunky modified IS300's floating around, that can bolt and drift very well...