You may want to search the subject over at the 335 series forum. Lot's of info on grouting blocks over there.
http://www.network54.com/Forum/119419/Some of the threads I've read have mentioned some deformatiton caused by the grout as it cures thus torque plate hone recommended afterward. Also have seen remarks about increases in oil temp depending upon fill. May be worth checking this out especially for high HP P'car.
Kelly