Upgrading my 340

OP, in reading your uses for the car, keep in mind that doing lower track ET's can work against good driveability; it doesn't have to be that way but a lot has to do with your present parts inside the engine. A lot of 'driveability' is subjective, so let's keep that in mind.

Can you help us with:
- The pistons inside your engine? A part number and brand will do.
- The cam in your engine? If you don't know specs, then part number and brand will do.
- Is this a stroker, or did it use the stock type crankshaft?

For me, where good street driveability is a top goal, the 6 pack is not the way to go. I don't perceive that you do a lot of tuning, and while a 6 pack can be done, it is not a simple task. The whole original need behind it is actually outdated IMHO; newer single carbs can do the same and are a lot simpler to work with. So the main value to anyone is that it IS a six-pack, and if that does a lot for you, it can be worth it. But it will cost you in street operation.

Good headers will help you ALL across the RPM range so that is of great value. The right tube size and is important. If a long collector is not available, then consider adding one, as that helps low end torque; that all helps in driveability.

Different carb brands can have different general characteristics; a "spreadbore" type will have smaller primaries and will tend to be easier to tune for low speed use, but a lot of carb selection seems to be what a person is comfortable with. There is enough tuning info out there to make them work.

BTW, if you have 320 HP at the wheels in a chassis dyno, then maybe you have 360 HP at the crank as a guess. As a very rough estimate, you have 10% more peak power to possibly gain assuming the AL heads you now have are Edelbrock Performers. Is that what they are?