Taking to a recommended transmission specialist today. It all needs to come apart anyway as the gears will be replaced with either a Getrag or PPG box. Agree that sandblasting looks good, but for the level of build we're doing it needs to be coated. The entire underbody (subframes, arms, diff, etc) has been stripped and will be coated while the car's on the rotisserie for paint.
Thanks mate. Getting it done this week... professionally ?