Trick Flow 240...

All that sounds great, but how much better than stock can a fully bolt-on cylinder head be,

That is a ultra broad & general question so the answer is the same.

An easy 100 hp to 250hp and more.

Reason? Build dependent as well as head dependent even though the answer is focused on the TF head.
and exactly which segment of the big-block Chrysler market are Trick Flow’s new PowerPort 240 aluminum castings intended for?
High performance street and low to mid level track performance.

Why? Same reason as above.

It is not a racing head. But that doesn’t mean you can’t race it. (Certain) MoPars Stage VI S/S - racing head would port out to about the TF level. But that was yesteryear, it’s now this year and things change.