I’m going to throw out 290-300rwhp, and 320-330rwtq. I had a 331 with the TFS top end kit, never had it dynoed but that’s what I always assumed it was around.
331 is completely different than a 306 and I know you know this. My 306 made right at 310+ rwhp and my 331 makes right at 370+ rwhp with the same induction setup as my 306. I have overbuilt the induction on my 306 knowing I was going to move up in cubic inches.
Just noodling around on the internet you can see most post up numbers in the 290 rwhp and 300+ torque on a dyno with a TFS top end kit on a 306. TFS lists fwhp so you have to take into account drive train losses. They are well thought out kits and you just need to know where you want the power band so you choose the correct heads, intakes and cam. Call them up and talk to them as they are super helpful.
I don’t know HOW of a difference it makes but I did have my 331 built with lower compression (9.5:1 if I recall) as I originally had planned to supercharge it.