Can you give a more definitive answer?? When "Scatpacktom" wrote, "One thing to consider is that the X head was designed for 2.02 valves and the J head was designed to use the 1.88s. These two heads have very different short turn shapes. Even when the factory installed the 2.02 in the J they didn't fix the problem. The "area under the curve" That the chief mentions makes a huge difference. Make sure you give the short turn a tune up too ".
Although porting will tremendously help flow (and horsepower) it's not as critical when you're trying to make torque. My question is based on what I plan to build.... I have a set of 360 heads, 1980-85 596 heads. I plan to install 2.02 valves and had asked (earlier) if the hardened seat area would be completely removed when the machinist cuts the valve seat for the larger valve. But like some of you are saying the 2.02 is an intake valve and the intake seat doesn't require hardening. So as long as I stay with the stock exhaust valve size I'll be OK on the hardened seat issue. I'm building a 318 stroker (390 CI), no high RPM/revving. It will be a torque monster, since I have a 2004R overdrive already installed I won't need high RPMs to putt around the streets or on the highway. I do plan to port the heads so that the 390 can breath but nothing above 5800 RPM. As it is, If I did my math correctly at 5500 RPM and the 2004R overdrive I would be cruising close to 189 MPH with the 3:73 gears I currently have.
Since the 596 heads were made for a 360, if they are ported they should be able to support a 390 with respect to having plenty of torque. If I was planning on making as much horsepower as possible AND turning high RPMs then I would really need better heads, correct???. So my question, "What you said is true for horsepower right?? If you looking for torque then it wouldn't matter as much...correct??", is asking if I will still get plenty of torque in my scenario because horsepower isn't as big a concern since I'm not planning on going above 5800-6000 RPM??