Any reason it has to be cast?
Ij40 is a 7 year vinyl. Its what 3m recommends for flat signage. Ij35 is a 5 year. We use ij35 on real estate signs that we expect to be garbage by 2-3 years, and ij40 on long term signs .
Calandered gets a bad rep due to all the cheap crap out there.
There are two kinds of calandered... Monomeric, and polymeric .Monomeric is garbage for vinyl, and what most of the cheap brands use. 3m, Avery, even most oracal calandered is pretty good. Not 10 years like cast good... But still pretty good.
Ij40 bundle is about half the price as a 180 bundle for us, we've been using it on all our flat signs for awhile, and no complaints. I do everything from beginning (printing) to the end (vehicle installs... Sign applications) and ij40 feels like 180 to me, just not as stretchy... Which is expected in a calandered.
If your ok with trying a good calandered, I'd give ij40 a try. If you already know about mono vs poly vinyl, and want cast for a different reason.... Sorry! Most people just hear calandered and presume it's garbage, so I point it out that while mono calandered (the $100 rolls you can buy on ebay...)is crap, the more expensive 3m/avery ones arent.
We wrapped our work vehicle in 180 - we were just starting to test ij40, so I decided to wrap the back of the vehicle in it since it's pretty flat. Its been 6 months, so not too long... But so far it's holding good, and no shrinkage at all.