How low can one lower the 914 front before suspension geometry needs to be corrected by raising spindles. 911 struts will be used for street.
THanks

You can partially correct the steering rack geometry with simple spacers or fancier kits like Elephant or ERP make - very popular and cheap mod. The bigger issue, as I understand, is the loss of suspension travel which raising the spindles gets you back. Sorry, I don't know the exact point of lowering at which the mod makes sense though.

Just keep in mind you need to have the tie rod parallel to the ground when the car is static. The 914 is an old car so it is common to find cars that have already been adjusted, and some (read most) are done improperly. So, if lowering the front of the car, take note you need spacers under the steering rack (or some kind of other bump steer kit), as Chris said. And keep an eye on the tie rod and shock travel. You are not going to want to lower it much more than about 15mm if it will be a street car. Any more than that and the bottom of the car will suffer when you forget to take any remotely steep driveway entrance or speed bump at an angle. The gas station entrance will get ya every time, if not careful.