Setting it by ear isn`t good enough. A TBI systems timing can be under 0 and still run. You have to know where the timing is on these engines.
The factory spark advance already greatly limits how much it gives, and if it don`t have enough timing it`s not going to have any power.
Get a knock sensor for it, if it runs into detonation it`s not going to know
to retard the timing which can result in engine damage. If the engine has the stock for the year it was made heads they have large inefficient chambers without swirl ports, which means it`s likely going to want more timing advance. Get some timing tabs, get a light, pull the computer wire and check it with the light. Factory calls for 0, but being it has the older non swirl port heads you can likely give it as much as 8 without issues.