I was on the TF34 development/deployment team, & visited Farmingdale when the prototypes were being assembled. The cost and survivability disciplines were very much in evidence. I even met Kartveli, who maintained a desk in the engineering office. He thought it the ugliest aircraft ever, but fully understood the mission and requirements.
The unique and biggest airframe/engine integration issue would be gun gas ingestion into the engines, but the GAU-8/A gun was the be-all and end-all of a successful program. GE had a lot of work in solving the inevitable ingestion problems, but got the job done.
