There are three reasons for sleeving 351-C lifter bores. The first is to correct extreme wear due to high mileage or high rpms resulting in egg-shaped holes in the cast iron block, and resultant multiple pressure leaks. The second is to reduce the monstrous cast holes feeding the lifters to a more reasonable size for high speed oiling improvements. The third is to correct lifter bore angles relative to the camshaft and crank. Only #1 is important for street cars, mostly to try and rescue a worn out block.
BBCs are notorious for factory mis-drilled lifter bore angles while Clevelands are usually darn close to blueprint specs. Note both are stagger-valve performance V-8s. BHJ's expensive fixtures and jigs allows indicating what you have with precision measuring tools, then boring and honing the bushings at the proper angle and size to correct this if necessary, not just assuming the factory angles were all perfect 50+ years ago. I'm unfamiliar with Wydendorf's requirements.
I would never consider doing this at home- even with the BHJ fixtures, and I own a small, complete machine shop with 40 years of experience. This is not a hand drill/hone job but a pro racing machinist's job with the proper tools. Preferably someone that's successfully done it a few times before so he doesn't have to learn on your block at $125+/hr (with results as mentioned).
I sincerely hope this butchered block is able to be rescued. Usable factory ones are not easy to find these days. You may find that one of Tim Meyer's or Drag-Boss Garage's new replacement iron or aluminum blocks will be cheaper and better. Good luck-