As noted I wouldn't put the X any further fwd than necessary. If there simply isn't room btwn the engine and the radiator for it then fwd of the radiator is the likely only option left. Recall that I said to put the tube intersections where the loads are. That's also what autoxcuda is talking about, feed the K member bolt loads into the tube structure directly. That requires notching into the OE box section or something to get right to the plates that the bolts thread into.

Ideally those bends in the upper tubes would also have a tube running from them to the center of the cowl/dash bar (the "export brace" in Mustang terms), but only if the cowl bar can feed those loads further into the tube structure. I.e. if it too is bent at the center to meet those tubes at the cowl and re-direct the loads to the windshield post tubes, which then distribute the loads throughout the rest of the structure. It's 3 dimensional truss design, think in terms of triangles - anything else will flex.

On a couple drag cars that I've worked on I built a fore/aft engine locator bracket that bolted to the OE engine mounts and had a pretty serious strut that bolted btwn it and and somewhere on the chassis - specifically to stop the plate from bending due to engine inertia.