My idea would be to not buy hydraulic ebrake, but use stock ebrake, with maybe just changing it's button to 'drift-button' (and removing mini spring behind it). Stock ebrake placement seems well fitting for such uses
If you really need parking brake a lot for frequent drifts/making up professional & drift car .. aren't they mostly with stripped to bare metal interior anyway?
If car is mostly daily driven one you ocasionally try to drift for fun .. i somehow noticed that in most cases i used accelwork/clutch hits/swinging car with inertia instead of ebrake pull, hence i put spring behind button back).