I bought a vf39 with 50k on it for 350 and it had the famous waste gate crack. Crack doesnt matter, most of the ones youll find will have a crack. If it doesn't have the crack you'll pay a lot more for it for really no good reason. I installed the turbo with catless FP, apexi noir exhaust, turbo inlet (put that on that on the must buy list or I can guarantee you'll have a boost leak), sti tmic and splitter, walbro pump and an AEM short ram intake and grimmspeed EBCS. At the time with these parts the car was pro tuned at no limit motor sports by Clark Turner and Dave Brown and the car made 290whp/350wtq on a Dyno dynamics Dyno.
Depending how you drive the car will determine how long the 5 speed will last. I wanted more power so I did 1000cc IDs, 38mm gate and up pipe, ETS TMIC, TGV deletes and a Perrin 3" exhaust and my car is making 360/411 on E85. I drove it around for a few thousand miles and then the clutch started to slip so I put a brand new 07 STI transmission in it...be prepared to spend a few thousand to do the swap...I would say if you don't launch it and Smash the gears that you will be ok with the 5 speed...all depends on the driver.