Sadly this block was machined about 5 years ago then I stored it. So no chance of anything out of them.Call Ted's for a used one off a blown engine or maybe Lerory Diesel. Any luck with the machine shop? Seriously they need to step up for putting you in this situation of loosing "classic" "collector" or otherwise "rare" parts.
Like The Challenger Space Shuttle you will get away without the bypass till you don't. Likely on a cold day. No flow of cold oil (Oil pump bypass wide open at full pressure but oil not moving through cooler) starves bearings or high pressure pops something. You can see what our taxpayer dollars found with Low-Temperature oil Pumpability... in a 6.2. http://www.thetruckstop.us/forum/threads/low-temperature-oil-pumpability-in-a-6-2-internal-oil-flow-info.41477/