Another rust repair question.

[MacsGTO]

Hey all, thanks for checking on this thread first of all. So here's what I'm looking at. I have a '65 that is fairly solid. My forward driver's side cab corner/mount is rotten away for the most part. The sad thing is that other than a small spot here and there the truck is really solid. I do not have the means to lift/store the cab or rest of the truck while repair work is being done. I would like to fix this as it would be a shame to let this one go to waste due to this one area. Is it possible to fix this while it's still on the frame? Not so much mounted but I'm thinking take the mount bolts out, jack it up cut/weld, prep/paint, replace mount bushings and set her back down. Begging for someone with experience to chime in. Also to add complications, I'm going to have to outsource this to someone to come and do it because I have zero welding experience. How hard is this particular replacement job and what could be the average time frame to get it done? Thanks for the patience of dealing with a nOOb. Very respectfully, -George