eterna,
I owned a real VR4 back in US. I was fun to drive, especially in snow. haizz..
About your car, you said 2-3minutes, then 6krpm going up hill at 5km/h, you could have toast your autobox. Too much heat.
Like Joegoi said, your torque conver is gone. I would do the 4k fix.
8k don't guarantee a problem-free future
How about a "experieced" (used) gearbox ?
p/s: I want your GSR