Ok the best person for you to talk to about this is Andy G, he has an E23 Alpina B10.
If you want to go for the Alpina look then you will need Alpina wheels and the front and rear spoilers.
From what I can recall the car also had a full Bilstein Alpina suspension set up but Andy knows best so will be able to help with that.
The original car came with the 16" Alpina wheels as fitted to the E24, E28 Alpina B9/B10's at the time. The original open type with black centres and no locking cap. These usually come up on Ebay in the UK and Germany regularly. But as your car is a 7 and quite big I think a set of later 17" as on the E34 Alpina B10 would look awesome. The 17" wheels are easier to find on Ebay as they come up regularly. But go for the 5 series versions as they are 8.5" and 9.5" as the E32 Sevens were 10" wide on the rear.
As for the front and rear spoilers, they were just a lip that went on the front of your car and was not a replacement bumper. They are very rare now as they were all made from fibre glass at the time and very expensive ( I have lost count of the number of Alpina spoilers I replaced back then, before Alpina started making them out of PU Rim). Again Andy G is your man for this and may be able to help. I dont think you need a rear spoiler and again they are very difficult to find. I have included the best picture I could find of a car with the spoiler on it, and a very poor photoshop of how your car would look with the later Alpina 17 Wheels as well.
Oh nearly for got if you go on the unofficial Alpina homepage you will find details and more pictures of the front lip, albeit on the earlier cars but looks similar,
www.alpina-archive.com under the 7 series section.
Hope this helps
Regards
__________________
The BMW M5 (c) 1984
The ORIGINAL & BEST.............

Imitators include
Any AMG, RS Audi, XJR TATA sorry meant Jaguar
I am sure BMW are flattered
ALPINA in one word.....PEERLESS