Opinions wanted.

So I have a 1966 mustang that I am currently converting from a 6cylinder. I am at a point where I just started working in the real world as an auditor so now money is at a bit more disposal. I was originally planning on a cheaper method and now am at a crossroads where I don't know what to do. I am looking at this mustang I have and it has rust spots and bondo in places and I am going to want to get it fixed. My question now is, is it worth it to have the frame rust fixed and engine compartment rust fixed or would I be better off finding a donor car 65-66 that is rust free.

I have all the parts that need to go onto this car so I would only really need a shell that is rust free. What do you guys think I should do? Should I try and search out a rust free shell to adapt all my other parts to or should I fix what I have. I will not be doing any of the body work myself so that isn't the issue here. The issue is what will cost less in the long run.

Thanks.

I'll snap some pictures in a day or two of the problem spots that I'm finding. I just feel like the body needs more work then I want to have done to it. if that makes sense.