To expand a little, you don't "need" hto's or colder plugs right off the bat on a basic setup, somehow that seems to have become the norm over the years. Compression, boost level, fuel type, iat etc will come into play when selecting the best plug heat range and gap for your setup. I have found the 3v likes some heat to make good power so dont feel like you "have" to have colder plugs or colder tsat etc, look at your setup and make a determination based on your goals. I felt like there were drawbacks of having colder or too cold plugs for what the setup needs, namely cold start drivability in cooler weather decrease in mileage etc, not a big deal if its a weekend or drag car, but if it sees regular street use might be a little annoying. In general 8-9psi 450-475hp range on a stock block with 93 or e85, the car seems to perform better with a stock heat range plug gapped appropriately. I would also take a look at the plugs after the setup is up and running and tuned to see if they are too hot or too cold for your setup. You can google or hit up youtube to see how to read a plug. If you have higher iat's with like a twin screw or procharger might want colder range just to keep things safer. I had colder hto's for a bit when I ran 93. When I started running e85 I went back to stock heat range with ht1's car feels better/smoother in the lower rpm range and runs good and makes good power. And I still run 93 with them as well. I run 12psi on 93 with them and 16psi with e85 760rwhp. Keep in mind my setup has ambient iat;s at that power level and motor is 9:1 compression. When I pulled out the ht1's after a year or so to put in a fresh set they all looked great still so stock heat range at .028 gap seems to be appropriate for my setup.
In general 10psi or less on 93 or e85 with decent iat's and stock compression I would keep stock heat range plugs and just check them out make sure every thing is good. If running more boost, more compression or have higher iat's then you can start stepping down to colder heat ranges as needed for the setup. Also the go to gap has become .032, I am a believer in only running the tightest gap you have to on the setup to run good and not get blowout. Car runs smoother with amore complete burn with the wider you can stay on the gap. So if your running 8psi 450hp try a gap in the .034-.036 range and see how she runs. And just gap down as necessary for the setup.