I purchased an oak headboard and footboard that is turn of the century and for a full size bed. It came with siderails and slats for the box spring and mattress set. I would like the headboard and footboard, which are each tall and heavy to rest on the floor and be secured to my queen size frame. If the siderails would work in this scenario, all the better!
Surely there is a simple solution to retrofitting/adaptation, but what is it?

I don't think that you are going to be able to get the side rails to work in this situation. You've got a full-size head board and foot board. And, you have a queen-size mattress and box springs. Is that correct?

What I'm picturing here is that you would have to retro-fit length-wise, boards that would be underneath your queen-size bed and connected to the headboard and foot board. I don't think that your side rails are going to work in this scenario.

That is my take on this anyhow...

Perhaps someone else will come along with some additional ideas for you.

I've been away for a while, so I apologize for the delay in answering. Clough is correct, this won't work. Adapters are made to put a queen or double headboard onto the reverse size bedding, but always ignores the footboard. If you're really determined to have this done, you could have a local woodworker work with you to design new siderails of the proper length, but this would probably necessitate some cross-piece on both the head and foot boards. Be advised, depending on the gross width measurements of your newly acquired pieces, your bedding may extend 3" or more on either side.