The reason the answer is not clear is because it is opinion based and not factual. It will be up to you to make the decision of if CNC ported heads are worth the expense.
I would say that depending on what turbo you go with you may not need to upgrade the heads to reach your power goals.
If you want straight opinions from others (which again will vary because peoples opinions do), I reccomend giving some more info. What kind of turbo? What budget do you have for everything? How reliable do you want the car? Ect.
1995 Z28 383 D1SC.... under the knife. (previously 624 RWHP)
1998 Formula WS6. MS3 cam, 5.3 heads... 441 RWHP