Technically, it isn't a vacuum hose since diesel engines don't create any vacuum. It is a Crankcase Depressurization Regulator, CDR, hose.
That out of the way. There is very little pressure on that system if your rings and valve seals are decent. Maybe 5 psi max. It looks like from the picture that the one you have broken is the one that goes under the tuna can looking CDR instead of the pair on the intake manifold. Correct? If so, it died because of the build up of oil over the decades. Clean it with soap and water and wrap with Gorilla tape. I know it sounds trashy, but its function is to hold in a little bit of oil and blow by.
I am sure someone will post up that they have a spare 30 year old elbow for a nominal fee. I have several but don't like selling rubber parts of that age. As you found out, straight heater hose can't make the bend. I made the entire CDR system on my Cowdog turbo 6500 engine. I used a coat hanger to make a template of the bends I had to have and cut out the length I needed. Then I convinced the O'Reilly's people to let me go compare to pre bent heater hoses they had hanging in the back. I found almost an exact match and it works great. All you need is to find a 3/4" heater hose with a 90° bend somewhere in it. Easy.