Hey. Nice Touring - I did exactly the same as you a few years ago with a Laser Blue 320i Touring
I bought a set of GAZ coilovers a few months ago. Very highly recommended, especially over the cheap eBay sets. The Gaz ones can be bought through RPM here on the zone or through their website. Check the trader section. The GHA coilovers will be good enough for you - they still have full height adjustment and damper adjustment.
GAZ construct their coilovers on site for you - if you send a set of front struts they do the welding and finishing to make your front coilover legs. You can choose whether you want separate spring/damper setup on the back, or true coilovers, like the ones in the image below. Note that for a true coilover on the rear, you need to upgrade your rear top mounts.
They come back looking like this:
They go so low you can sit the sump on the ground.
I fear you may have overlooked how far those rims are gonna stick out though - 15x10, plus the porsche adapters is gonna make them poke a LOT. You're going to need to weld some new, wider arches or something to get them to not scrub.