its not a bevel , its a worm and wheel underslung and the 1200 vw engine will produce far more power than the sunbeam could dream of , they did ware at an alarming rate and if the oil dropped low more so , 25bhp for the vw sounds about right but for the sunbeam sounds high , i had one for a short while and it was a well built slug , a m20 ,vb , m21 , (infact must be one of the slowest 500 ive ever owened) etc would leave it standing , looks like a nice project and vw parts are easy to come by , never seen the hub conversion you talk of but sounds prommising and worth fitting