Welcome to the site m8. regardless of which motor you go with , please allow me to offer a bit of advise . If your able to find an old rubber bicycle tube Cut it up & wrap some rubber around the frame so the bottom of the gas tank rests on it this will cut down on serious vibration as well as keep the tank from vibrating loose and saved the paint on the bicycle as wel.
I use rubber and some reversed gorilla duct tape so it sticks to the frame and the tank when you mount it also "LOCKTITE" is your fried when building these Some good advise is to build the bike ride it a little then sit down with a cold pint & have a go over each nut and bolt again this time use the lock tite chances are you may have to make a few adjustments and its best to not have them covered in locktite until your sure you don't need to removing said nut or bolt again .
I also use a small chunk of tube rubber on both motor mounts frame side and mount side . It really does help out a lot then I also use a 3"chunk of tube to hold my clutch lever in when rolling the bike around or in & out of the house. The best advise I got from these wonderful folks on this site is to NEVER EVER remove or snug down a head bolt or any bolt on a hot motor the threads will get destroyed
The factory provided spring locking clutch lever is nice but do not trust it while the bike is running "IT WILL HURT YOU!! " all you need is to tap it slightly and the clutch will spring release the clutch causing the bicycle to lunge forward.knocking your big brothers beer out of his hand & pissing hi off royally Esp. after he just got done telling you not to trust that spring ...but you didn't listen nooo !!
..In case you didn't guess that last part actually happened to me !
Good luck with your build M 8
P.S. I actually do know how to take pictures I just had to chop this one to make it fit into the 2200 x 1500 pixle req.