Many year ago I put a 390 into a '56 Bird for customer. The real problem was the oil pan as the FE is generally a front sump engine while the Y block in a Bird is rear. I had to cut the pan down in the front and raise the engine as high as I could and still get hood to close. The Bird is a rear steer car so this again interferes with the pan and oil pump. The 390 just had a small cam, headers and some compresion. I used a close ratio top loader for tranny. The Fe certainly livened up the Bird. I don't remeber motor mounts I used and if they were a problem. An engine with the oil pump in the rear would be easier to install. Hope this helps. Good luck.
