I'm lost.

I can't work out what you have done and what you are trying to do.

What was 8.1 running on?

Normally to install an OS you have to have booted from a different device than the target you are going to put the OS on.

Do you have anything at all to boot the 1400 from?

Where did the 7.6 image come from? Who made it, and what from?