A continuing work of art! I'm an utter newbie with respect to building an engine, much less something of this amazing detail and quality, so I hesitate to offer any suggestions ... but though I have not yet built an engine, I have been an active home-shop machinist for around 14 years. So with trepidation and humility, hoping I am not guilty of going too far off topic, here goes: With respect to the problems you had with boring the StressProof ... I have gotten excellent results machining stress proof with HSS tooling. In fact, I have generally gotten excellent results machining the vast majority of materials using HSS tooling - I have been surprised that so many of the builders here seem to use carbide exclusively, even on machines that arguably would do better with HSS. A stout boring bar definitely helps, of course, and so does a stout way to hold it. For much of the boring that I do, I mount a tool in my quick-change tool post. But when I need the ultimate in rigidity, and especially a larger size boring bar, I turn to an "Armstrong" style boring bar holder. No, not the lantern tool post tooling; rather something like this: This is one of the very first projects that I made on my lathe, for my lathe - very easy to make, and works extremely well. Here are pictures of the components and assembled unit: Again, I hope that I am not going too far off topic - if needed, I will be glad to delete the post!