I don't like to deviate much from the original design on an AD. The 6 cylinder is really native to it so I stick with that. I DO go to the next generation 235/261 (54-62) because they are full pressure oilers and insert bearings. I take the block and head to the local engine shop for hardened valve guides, cleaning, decking, magnafluxing, boring, etc. I like to buy the rebuild parts and kits from the same engine shop, then I assemble it all myself. No better feeling than starting it up after all that work and knowing you had total control of the quality, etc yourself. They are pretty straightforward to rebuild and something I enjoy. Not for everyone.
