Project Update. Went a very different direction. Instead of mucking about trying to find good street winter tires went to more aggressive studs. Used Endurance II ice racing screws + washers/nylon nuts on the inside, x70 per tire, in a set of old all season I had on Volvo wheels. After one weekend was very happy with this route, tons of grip, great car control, but can still get the car sideways when you want to. The biggest limited factor at this point was the open diff. My buddy noted that since the car uses a Dana 30 rear axle we could use a Spartan locker for a Jeep and be way cheaper then a LSD (but more drivable then welded). Got that put in and ran at Winnipeg Beach. Pretty quickly found that the weight over the rear axle was entirely unneeded, and actually made the handling worse as the car would spin out easier. So took all the weight out of the back and now feel like the setup is dialed quite well for ice drift antics. Can still get it to spin out if I my throttle inputs are off but seat time will fix that I'm sure.