I am not knowledgable mechanically so forgive me in advance. I have a 72 demon with a 340 block 69 and 360 heads with a purple cam 282/482. The 360 heads are 1.88 intake 1.62 exhaust.
I have a complete set of X heads with 2.02 intake and 1.60 exhaust...
this is a 4spd street car with a weiand dual plane intake and 2.25 stock exhaust manifolds. 355 rear sure grip.
Will I have any noticeable power/torque swapping the heads?
The only difference between those two sets of heads is the size of the intake valve. The ports and chambers are the same size (at least they're supposed to be), if you put 2.02's in the 360 heads they'd flow exactly the same as the X's. Swapping the 360 heads for the X's wouldn't buy you much at all with regard to cfm flow. If you had some port work done on the X heads it might be a different story, but your engine set up isn't super aggressive to take advantage of a lot of extra head flow anyway.
You can look at some flow numbers here, some of the 1.88/1.60 heads are shown as flowing just as much or more than some of the 2.02/1.60 heads. I would expect most of the time the 2.02/1.60 heads would flow a little better, but given the factory tolerances that's not always the case. It's no massive improvement anyway.
I doubt you'd notice any "seat of the pants" difference at all. And of course you run the risk of changing the compression ratio for the worse, stock head chamber volume was anywhere from 65 cc's up to 72cc's. The X's weren't any better than the 360's for chamber volume, and there's always a chance you have a set of 360 heads that are on the smaller chamber side and a set of X's on the large side. So you could actually lose compression ratio. Now, more than likely they're pretty close to the same size and any difference would be minor, but you never know. I have a set of later 308 heads that have 65cc chambers.
