Sorry, didn't mean to confuse anyone.
Going on an stock-ish 340 street car. The cam and intake system can't make use of the extra flow that would be available at higher lifts from the big port/valve Shocker 185. So it doesn't make a lot of sense to spend $1000 bucks now for performance that will not manifest itself until a new motor is put together. Sorta like putting a set of TF or W2's on a 340/360 but not changing anything else, it should make more power, but there is going to be a lot more head than the engine can use.
The 171 version flows same or a little better than the Edelbrock heads and that will be a good improvement from the J-heads and still be balanced.