I'd also re-run resize2fs after changing the partition size. That way the fs will be resized to the actual size of the partition. If you're doing that, you can make the intermediate fs size much smaller than the target partition size, and not have to worry so much about the fs-bigger-than-partition issue you hit
Ah thanks! I missed this from the resize2fs man page:
"If size parameter is not specified, it will default to the size of the partition."