If you're looking at a Euro motor then I'd point you towards the S54 swap. More reliable, easier to find parts, and more powerful. The S50B32 can be a great value up front but once you start importing regular wear items from Germany you start to understand the appeal of the S54.
Also, make sure you actually try out some of these motor setups. You may find that you dislike the power delivery of a centrifugal blower, as I personally do. They're great for numbers but really don't make the car as fast as you'd expect due to the high-rpm torque delivery.
I'd suggest revising your paths to the following:
1. S50/S52US (210-220rwhp)
2. S50/S52US with cams/boltons (240-250rwhp)
3. S54 (280+rwhp)
Just my personal opinion. In the spring you can come by the shop and feel just how entertaining an E36 chassis is with an S54B32 strapped into it.