Definitely replace the stock tank. I used the stock one at first, thinking that it looked tough enough, actually i was just too lazy to buy a new one, and it lasted maybe five or six flights before it sprung a leak. I replaced it with a dubro and haven't had any problems since.

My old style 63 has a soft mount on the Laser 3D and it works great. I also mounted the engine upright which took some head scratching because of the size of the mount, dubro as well, but it worked out okay.

I've got a couple hundred flights on it now, and though I have considered pulling the engine out for another airplane, I'll probably fly it until it comes apart. Touch and go's at the bottom of a square loop are a blast with this thing!

Good luck on the build, you'll love the plane.