Kolari has a new thin stack conversion for A7 and A7r.
Thin Filter A7 Conversion Service for Legacy 35mm Lenses | Kolari Vision Infrared
Roger at lens rentals has his blog on this and D-Lloyd also. My own A7 sent off for the conversion.
LensRentals.com - A Thinner Sensor Stack
diglloyd: Modified Sony A7R Sensor Glass: Impact on Rangefinder Lens Performance