When anyone have to make new soft hose then have to use current EPA Approved Refer Hose type(s). Anyone making hoses for Vehicle AC hoses has them and tools etc to install them.
⚠️ Bigger issue is AC open to air for days is often a "problem..." For Months to Years then AC system is Totally F'd because very likely has dirt, water, road salt, etc, inside causing weak spots and leaks in metal parts. As is, "Flushing" often fails in 1 way to many causing "Black death" and other fatal problems. Worse for systems left open letting any crap in them.
Even taking each part out to flush a part at a time doesn't get all crap out. Worse is the evaporator never get flush because how their made. Flush often blow thru and crap stays and gets loose at any time later. (For many Newer cars, the condenser have same problem for same reason because many to most now uses micro channel "tubes." Many look same to you as Fiero etc on outside but isn't where it counts and block channels simply won't flush.)
Even people w/ system no pressure for years often have water getting inside doing same.
You can't flush the compressor or acc/drier so need to replace them.
(If compressor on "new" motor is V5 or V7 types then likely will need some rewiring to work. V types do not run wired as clutch banger to regulate system pressure in older I4 or all V6 Fiero..)
So If you seem to "fix"/"restoring" this... note can fail in days to month later w/o warning. Many Engine swaps uses 1 Serpent belt driving everything and you better hope you are faster then belt dying if the compressor jams.
Likely only reason AC compressor is still in there because the pulley is just an idler to make OE belt to work. Compressor can be dead otherwise.
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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave