If you add the 201 windshield and cowling, along with gap seals on the empennage and wing roots, will an early F be as fast as a J model? Doesn't the J also have a fairing on the vertical stabilizer? Although on a pre-1970's F, it should have a slightly less empty weight with the manual gear/flaps... How much speed do you lose with a 3 blade McCauley prop?   Thanks!