nice find.
do you have glass fuses in the fusebox as well? if not, and running the ATO or ATC fuses I like to use these inlinw fuses for add on stuff that hasn't been run through the regular fuse box like normal. these ones have a little cover that seals off the fuse for marine use but that cover also has a screw hole to mount it out of the way of mechanical damage like what happened to the plastic one you had issues with. there are others without the cover or, if you are in a bind and just wanna get it going, you can use an ATO/ATC fuse with the crimp on connector to match the spade terminal on the fuse. then make sure to use shrink wrap that covers the metal parts or at least tape those so they can't short on anything.
if it was me I would work on the system/charge the system in the shop, like any A/C shop would do. when you drive past an A/C shop you don't typically see the boys outside working on cars. the air conditioned shop would have less ambient humidity so less chance of moisture in the system. the only issue would be getting the vehicle hot enough inside when testing. you could do all the work and vacuum testing inside. charge the system, then run it and see what it does. then when done test it outside and see what you get for pressures in the heat
https://m.littelfuse.com/products/fu...e-holders.aspx