Thanks, crossmember is painted and installed. Surprisingly bolted right in, welding most of it in place must have prevented distortion.
It's been a while and I'm not done but I can see the light at the end of the tunnel so figured I'd post an update.
One issue I didn't know about (or had forgotten) is that the studs on the back of the R180 are shorter than the R160.
Double nut really tight, heat the aluminum a bit, and a lot of torque and they come out. Double nutted the R160 studs and torqued them in with some red loctite.
Used the conversion races from http://wordpress.suberdave.com/
The cheapest way to put an R180 in your car. R180 knuckles do have bigger wheel bearings and hubs and brakes but also a bigger bolt pattern, and this way I didn't have to buy knuckles and brakes.
Dave is a Subaru nut, check out his website if you're bored:
R160 stub is on the left, R180 on the right. Have never broken one of those but I have broken two sets of spider gears now so hopefully that's solved.
Stock (99 Legacy Outback) driveshaft on top, 2010 STI driveshaft on bottom. The 2007-2011 STI has the same wheelbase as the 99 Legacy so the length is right. I could have used an automatic driveshaft for my car and swapped the pinion shaft but...
The STI u-joints are much bigger (left) than standard. I also really like the fact it has three u-joints, some of the Subaru driveshafts have a CV joint.
Unfortunately the bolt pattern on the 2010 is a little bigger than the 2007 (what my diff and trans are from). The pilot diameter is the same though so I just drilled four new holes in the flange.
Trans and diff are bolted in, axles installed, rear suspension assembled. Driveshaft is in trans and diff temporarily. The hanger bearing sits about 2" farther back than the stock one so I'm making a mount for that. When I take that back out I'm going to replace the parking brake cables.
I also went through the front struts. Trying some voodoo which seems to be working, changed the valving a bit while I was in there.
I recently found out that these:
https://streetwiseparts.com/collections/bilstein/products/bilstein-universal-motorsports-strut-46mm?variant=1003419633&fbclid=IwAR3M9uVta1yIBAVRKTcX_y6dS3dcJz5TjtoGgum_SlrgzO3rtYuTDYHzQeQ
Include a strut housing you can weld tabs to and upper and lower spring perches. By the time you buy four of those and springs it gets expensive but it's an option.