As far as I know there is an upper bound of a block, which is one megabyte, is there a lower bound?

It was in terms of a race condition that I was considering this.

Imagine you make a double spend and then you try to propagate a block that contains only your second transaction. If so it would be much smaller, ipso facto easier to propagate around the network and get validated by nodes, isn't that right?

Maybe someone in the mean time would find a valid block for one containing many transactions, in which case it would be longer than yours, and maybe other miners would extend that- but maybe not.

Does anyone want to try this out on the testnet with me?

PS. I'm posting this here because I got no response on stackexchange