You could start by reading the whole thread as most options are covered
Then make a decision on what approach suits your budget.
The STi most common to the postfl BP/BL is the GRB onwards.
Same strut front top mount, similar trailing arm/3 lateral link rear with a shock that does less duty than the struts found on GD's. Eg rear camber is a function of the lateral links, not the strut top.
The STi front hubs can be machined to accept Wrx/lib struts, or use STi struts.
As mentioned the rear hubs are a trickier issue so I'd have to look at opposed forces to work out the similarities if any.
I've also seen Nissan 114 hubs that at least looked similar to the BP/BL hubs notwithstanding actual compatibility with Subaru driveshafts. And of course it's possible to get custom driveshafts made up.
The other most important benefit of the conversion is the larger 114 STi hub bearings which are purported to hold up better under severe duress.