A J Perkins 480 fits nicely in the same mount as a 400, it’s just a bit longer. It has a bit more poke in it.
1400Kv and 30A brushless motor/esc combinations are for nothing on e-bay, about £12 from a uk supplier, or dropping to £8.50 for 3 or more. Ok, forwards only, but a huge upgrade from a 400, and on a7.2 stick and 35mm prop, surprisingly frugal with the amps.
A 1000kv/30A setup has just been tried here and even with an x50 prop on it only takes12A. I think 8-ish A woulD be more likely on an s35 or s40.
Ashley