rb550four - would it be okay/effective to soak the interior parts in a 5 gallon bucket for a couple of days? If so, is there a specific glove I should have to handle the kerosene?
If you have Diesel fuel readily available, try it also for cleaning and de-fouling the internals.
As for the cases, elbow grease, Baby, elbow grease. A myriad of cleanser all work, but short of having the cases blasted with soda or other media, nothing will remove the grit, grime and grease of 40 years packed into the wedges and crevices that simply gets "sprayed on".
You "can" have the cases sand blasted by a pro, but that requires some careful work and knowledge on the part of the party doing the blasting. Even afterwards, significant clean up and rinsing and re-rinsing is an absolute requirement to remove any fine media from oil passages and threads. But, it can be done if you're diligent. Or elbow grease.