If only I'd have known....a cautionary tale:

When I removed the old radiator, I disconnected everything and after replacing the old radiator with a new one, I put everything back together, but a test revealed that the inlet casting was cracked, so a new inlet casting and gasket were ordered and at long last installed and everything gingerly cinched down. Another test and no leaks appeared so I tried putting the hood back.
No luck trying to line things up. No luck at all.
I determined that the radiator support rod wasn’t screwed in enough—but how much is “enough?”
I’m not there yet. There is a part of the threaded area where the threads are full of gunk, so maybe that will indicate how far the support rod needs to be screwed in?
I’ll find out tomorrow, but if I had marked the radiator support rod before removing the radiator—maybe with a bit of masking tape—it would have made things a lot easier,

Or not.
I still have 1/4 inch of clean thread showing and the support rod refuses to screw in anymore. This is on the radiator end of the support rod.
I gave it a shot of WD40 but that didn’t help. The hood still won’t align.
So near yet so far.

Well, the radiator support rod is screwed in until the hood fits well. That is its only purpose.

Maybe the threads in the new rad don’t go in as far as the old one. Check and see if the piece where the rod goes is the same length. Possibly use a bolt and count the number of turns after first engagement, and compare the two. Might also be able to look up inside and judge if the threads are equal depth.

I took some welding rod measured the depth of the bolt hole on the old radiator and compared it to the new one. The old hole was shallower than the new, but the rod met with some resistance when I inserted it into the new radiator, so I ran a tap in to clear out any debris and chased the thread on the support rod with the tap while I was at it.

Worked like a charm!

Thank you!

Good call. Nice fix.