Probe = cheap, semi-reliable daily driver. Leave it at that.
VR4 = Heavy, semi-reliable, expensive to mod/fix, and not really great at any one thing.
Ok, AWD helps you launch...but it's heavy, don't really need it. 1/4 mile track times aren't great because of the parasitic loss of the AWD and the weight slowing you down. Take it out to a roadcourse, you are destroying brakes and trannies. It won't even keep up with stock 240sx's because, again, its too heavy.
As for the Probe idea...at over 200,000 miles the engine is going to be too tired to handle any kind of upgrading. It will either need a solid rebuild, or a replacement if you plan on doing anything more than an intake and exhaust. An intake really won't help you out at all, just get a decent drop in filter. An exhaust probably won't help you out either. Increasing exhaust diameter decreases backpressure. Backpressure builds up low-end torque. However, a lack of backpressure does help top end, which is not something that would help you in the least with a street car. Keep the low end torque for leaving stoplights, leave your exhaust alone.