Need some help/advice about my truck cab

[68c10rat]

I bought a 68 a couple of days ago. I was told by a friend that the normal rust spots are ok and not to worry about it. Heres the deal though,the floors are pretty much rotted out,the cab corners are gone, the dash is rotted out on the pass. side, the cab mount on the pass. side is gone,theres a pretty good size hole under the dash as well. Also the bottom of the kick panels on the insides are ate up. There is some rust on the outside of the kick panel area as well,near the rear of the fender on the inside.What I am wondering is,is this the typical rust,should I try and fix it or should I start looking for a replacement cab or truck. I really did not know that much when I bought this one and I think that I gave too much for it now. I gave $750 for it. It has a step side bed that was wood but someone welded a piece of metal in the back of it. The hood is in decent shape and the grill is ok. The back window is alright for now,I havent taken it out yet,driver inner fender is good as well. I bought some replacement panels to get started with but I think I will be wasting my time welding them in. I took out the driver rocker today and it is ate up on the bottom of both a pillars as well,so I guess that would be another part to replace if I keep this cab. What is a good price for a decent cab?
thanks for any help and sorry for the long thread,but I need some help.