There are luthiers out there who won't work on Guilds, due to the finish being applied after the neck and body are joined/glued together, which means that the finish needs to be cut through before the neck reset operation can begin. Their fear is that the finish when cut through will result in a lot of finish work needing to be done after the neck reset is done, which they don't want to do. Mostly, it is ignorance and laziness on their part. I say this because it isn't just Guilds that are finished after the neck and body are joined; there are Gibsons that are made that way as well.
Find a good luthier, one who knows what he is doing with Guilds, and get a proper, accurate evaluation done. I am way too far from you to be able to help, and on the other side of the Canada/US border, but many here have had great results from Tom Jacobs in Florida, and I am sure that the board members here can point out others. The guitar is worth the effort to get working again, and pay no attention to those who say different.
High action is due to the guitar needing a neck reset, not due to the neck being warped. They are two separate issues, and as I said above, you need to get the guitar to an experienced luthier who know his way around Guilds.
He can give you a better assessment than we can here, mostly because he will have the guitar in person and not trying to work from pictures, so can make some basic measurements and evaluate things better. Do NOT assume that you need a new bridge, unless you know for a fact that there is something wrong with the old bridge. You may need a new saddle, and possibly a new nut, but those are fairly minor expenses.