Worth doing. I did that on my '68 C-code before upgrading to Edelbrock aluminum heads & their gen 1 EFI.My 68 289 2 V carb has the stock heads on it which are the worst 289 head you can get.
Would it be worth the trouble to install a set of 66 2v heads on it ? Found a set local that are pretty cheap
Tommy Hernandez did them purely as a favor because these days he's a FedEx exec but back in the 70s/80s he was the cylinder head guy for Dallas Motorsports, which was@GT289 who did the porting? I understand that you have been involved with some pretty heavy players when I comes to vintage racing of mustangs and small block Fords. Anyone can port match and remove the thermactor bumps. But your average guy can't port a set of heads to flow as good as those Edelbrocks. Like @1ofAMillion+ said how cheap is cheap. Sure $75 now. But what is the end cost going to be. If you just want a small bump in performance and are staying mostly stock, these heads if they are in good shape will probably work. But if you really want to bump up power from them it requires a lot more work and money.