-Scott,
I've done okay cleaning old intact grimy shimano white brake hoods by removing them from the brakes, soaking in hot water with dishwasher detergent, followed by scrubbing with a brush. Once the brake hoods are dried/ cracked, I've salvaged them by wrapping them with electrical tape, and eventually ordered replacements.
Here in New England, I prefer Sam Adams to IPA.
Best,
Larry