I'm not going to speculate of how much power a set of heads I've never seen or tested would make.
Someone will test both versions at some point, then we'll all get a real answer.

And, as with most things motor related......."It depends"(one of my favorite phrases).

But........ When going from std port to MW port..... In general, the bigger the cubes, the higher the cr, the bigger the cam, the better the intake and carb...... The more difference you'll see.
A 14:1 572 with an .800 lift roller cam with a TR and dual carbs will see a lot more gain than a 9:1 383 with a performer and a comp he268 cam.