Hi Andy Welcome to the site. There are many posts re building and fitting out Sea Queens on the site. You can search and browse. The boats in Harbour section will alsos give yousi details of the motor/prop/battery set up. I have an original Aerokits version and in my 48" Sea Queen I use a brushless 42 size 850Kv water cooled motor of 700 watts and it is happy driving a Prop Shop prop of 42mm at 45 amp on full throttle. Power is from an 11.1v Lipo of at least 2200 mA but Nimhs would work, just not as fast and less duration.
I purchased and built this kit, did not have any problems but found the supplied brushed motor was inadequate for the performance I required. So installed an overlander T4250 brushless motor with a 45mm prop. changed the battery for an overlander Lipo 4500 mA battery, fusion Hawk 60amp ESC. totally different boat as to the performance. Slight modification to the motor mount was required.