That factor is the main one.
These computer systems are alot and depending on how many sensors and what you wish to look at costs will jump alot.
The systems are only as good as the tuner period.
All of them including a stock ecm are fast enough to reach your speed goals.
It's how much you have...
While you have it apart.
At least mill the head.
Lifters springs etc.
With a strong bottom end you may regret later not porting the head.
Definitely some things to think about
Do yourself the biggest favor and get a hydraulic roller with good springs.
The stock camshaft is prone to wiped out lobes.
My engine builder won't even build one without a roller.