A moment's reconnaissance will tell you that the bonnet cable and its handle are not separable and can't be sold separately. Part #72233 comprises the cable (with non-detachable handle) and the cable housing. The easy way to deal with a frayed or broken cable is to remove it, leaving the cable housing in place, and just shove the new one in. And now you have a spare cable housing, which it is very unlikely that you will ever need or use. The purist, I suppose, will replace both cable and housing, but that's slightly (though only slightly) more work.
If the frayed cable breaks before you replace it, you can reach up alongside the battery, grope around with your fingers until you find the rod that connects the two hood-latch mechanisms, and shove that rod firmly toward the drivers side of the car. This is known as the Doug Meyer maneuver. Because it's a long reach and its success depends entirely on identifying the rod by feel, it is worth practicing before you need to depend on it. But don't try it until your engine has cooled down, since your arm must pass close to the exhaust manifold! A much easier alternative method is to (1) replace the cable and (2) using a length of bicycle brake cable (available cheaply in any bike shop), rig an emergency release that will pull the hood-latch release rod toward the right side of the car if or when the new cable frays and breaks. The free end of the emergency release cable might well be fitted with a loop, so that it is easier to pull, and might also be loosely coiled behind the fender stone guard, where it will be out of sight but easy to find and yank on when the need arises.
David Crowne in San Diego
David Ballantine adds...
Sorry David (Crowne) As much as I am in awe of the wealth of information that you contribute to this group, I am afraid that I have to disagree with you on this one. I have had to replace the cable release on my 74 Int. and was able to pull the broken one out of the sheath and replace the innards with a cable and handle from an MGB. I was then able to use the old one as a backup by accessing it through the vent on the drivers side. Undo the 2 screws that hold the vent at the bottom and slip your hand behind the vent and you can then undo the nuts at the top of the vent grill and remove. Feed the cable from the latch and attach some sort of handle, (a bolt for e.g.) and you have made yourself an emergency access hood release. (I seem to recall that either you, or Bill Spohn told me how to do it) cheers, David Ballantine