[Racer x]

Wow this is real
OK First I am very sorry for your loss. That is a tragic story. ALL the focus need to be on your daughter.
Doing things like this will be a great memory for her.
With any project you need to start with a goal. What do you want to do with the bike?

She is to young to ride a custom motorcycle in traffic. So show bike? Race bike? Track bike? Try to pin it down. It will save a lot of work.

Any of these bike will take you to a place with great people. And it's the people you expose your daughter to that will matter. Race people are great family people. The track is my home and the people are my family.

But building a show bike an going to shows is the same thing. And she will learn many valuable skills.

As for the bike. If you are going to do an engine swap. Definitely don't just buy a motor. Get the whole bike. You will need so many little stupid parts its worth it. Bent frame bikes are cheap.
I would go for the 650 engine . First it's is a pretty motor . And fuel injection can sit and still start later.
Keep us posted . We love photos. Get
Your daughter a dirt bike in the mean time. So she learns to ride.