Re your request for help on running gear for the MTB by Sarik.
I am unsure of the layout of this boat apart from some quick research.
It would be good to have a look at some plans re layout.
However having rung Sarik out of interest they advise me that Cornwall Model Boats stock suitable running gear for this model.I am a customer of CMB and have been for years as are many other members on this site.They are very good and helpful and if you check out their site it shows a comprehensive list of suitable shafts.
You can ring them on 01840211009.
I don’t normally build to this scale but attach some pictures of one of mine to a similar scale if they are of any use.
Is yours single screw,or more.
I would suggest either M2 or M3, but will stand corrected by those who build more of these types.The motors as shown in mine would be more than suitable,but again are you going to use brushed or brushless motors which will determine your ESC control.
Another good supplier of running gear is SHG model suppliers.
If I or any of us can be of further help please ask away.