My '87 745T was beyond boring (needed about .090" which of course no piston is available) Turbo blocks are hard to find in good condition due to failed intake hoses wiping out the cyl walls. I had my block sleeved back to std. A good machine shop can handle this operation and you will have perfect cyl. walls. Ask them if they can bore it using a torque plate, it will give you truer bore diameters with less distortion. My block has now accumulated about 110,000 mi and should be good for a bunch more!