Etype Ser. I front crossmember jacking

I have often seen referred to and a recent XKs unlimited mailing showed a piece of wood that fits into the front crossmember and can be used as a central jacking point for both front wheels. Over the 28 yrs of ownership I have stared at this crossmember, on my late l967 series 1 this crossmember has the radiator bolted to it in two places, out at the ends it is attached solidly to a from tube at each end. I have never considered this a good jacking method since the crossmember itself is flimsy to raise weight of front of car and feared any wood placed within in it would have to be strong enough not to flex and put pressure upward through radiator damaging it, all the weight would be focused on the very end inch or so of the wood. In addition, the bolts holding the radiator on protrude through the crossmember and into the space occupied by the wood, so the wood would need holes/indentations to allow the bolts to penetrate into the space, further weakening the woods ability to support the entire front end of the car simply on its two end points. Called Xks and parts guy referred me to technical guy who will call back. Anyone have experience with such a way of jacking car up, my crossmember is in good shape with just slight warp from end to end, someone may have tried to jack up from there and saw it would not work. All of this assumes I put jack under center of wood as opposed to using 2 jacks, one at each end.
Thanks, Jay, '67 Series 1, roadster

As you figured out (in your other post) the block and jack use the picture frame, not that cross piece below the radiator. The wood block is the way to go here - either one offered by the usuals or homemade. Mine is made from a piece of Trex and labeled to try to make it as idiot proof as possible:

And for those who may wonder, the block of wood is to keep the flanges on the bottom of the picture frame from getting bent when jacking.

Jaguar's factory service manuals say to use the wood block.