Re: Beginner fork and handlebar question
Welcome to the forum. You'll find a lot of help and advice here to get your first motorized bicycle project on the road.
Unfortunately neither of the bikes you've shown are very good candidates for an in-frame engine mount. The step through would be the least objectionable but the full suspension one just won't work. There are options such as a rack mount, chain or friction drive. Do some research on these mounting methods.
Good luck, have fun and ride safe.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"