I was going to write a smart remark about WidowMakers "its not about power" comment. But he did say "brute" power so thats alright. My take on the AE86 is having the right balance of power and handling.
Lots of options but from my experience I've had the 4AC, 4AGE 16V and a 4AGZE. I would take the Z everyday over that list. But having said that I am now turboing it
You could also look at the 3SGE or 3SGTE options but with higher development costs (engine mounts, intakes, GB issues etc).
What do you want to get for your 8K? Sounds like drivability and reliability. For 8K you can achieve a lot.