Bob and David,
In post #5 before you glue the fuse inner part, thats when you need to decide what fuel tank you are gonna use.
If its Dubro 8S as instructed you don’t need to change anything.
After that stage changing the tank floor becomes complicated.

As for motors, I put on mine OS 46 AX, it takes off with ¾ throttle swinging 11X7 prop.
I’ll put the OS 46 that I have with 11X6 prop this time.

In my opinion
I would use 2 stroke because of location of the throttle on left side on 4 stroke motor.
If the exhaust is on the right side then the switch, voltmeter, filler valve is on the left and in addition to add the throttle cable into there, it’s a recipe for a wire spaghetti.

On the other hand 4 stroke motor produces much less crap from its muffler, in my midstar the wing is getting filled with this crap.

Things to think about.

Alex