So I'm finally yanking the old 305 TBI and installing my 377(stroked std bore 350) with supper ram intake, +5cc Keith blacks 64cc aluminium heads. I'm looking at about 450hp at the crank I hope and trying to figure out what plugs to use on the engine, definitely going with platinums however I doubt that the stock temperature plug will not do, any advice on where to start?

Stock plug heat range will probably be fine. I see nothing needing a colder temperature plug.

A plug needs to be hot enough to burn off the deposits but not so hot as to melt the electrode. Run the coolest plugs possible that don't foul.

Platinum plugs are only needed when they're difficult to access or you're too lazy to change them regularly. A regular copper plug will work just fine, are a lot cheaper plus they're easier to read.

When reading the temperature range, look for the bluing on the ground strap about 1/2 way down. If the color changes near the tip, the plug is too cold. If the color change is near the base, the plug is too hot. New plugs are the only good way to read temperature.