Bad roads - need to get height of the Boxster.

[wjcj59]

Here's my quandary - The previous owner installed Eibach springs (on the original struts) lowering the vehicle. I want to return the car to the original height (very bad Michigan roads) with Bilstein HD struts & stock springs. Front stock springs are available, rear stock are not. Is there an equivalent spring available? Or is there a better way to get the vehicle higher?

I have a 1998 Base @ 52K miles, 18" wheels (225/40R18 Front & 265/35R18 Rear) and (as far as I can tell) no other suspension modifications.