Hi MS,
The 550 will fit straight on with the handle bar slightly tilted backwards which is all a standard part of the Model 45 set up.
I will say, if you can find a 14 inch Electric model 45 most of them have a Series 2 Style handle bar arrangement with the kinked lower end, why they were ever fitted with those I don't really know apart from a few of the later petrol Briggs fitted engines using the large fuel tank and requiring this new set up, but it's more than likely by that stage all the later 14 inch machines had the same kinked version fitted whether they needed them or not as they would've discontinued the straight bar assembly.
Cheers,
BB.
