The Franklin (CV13) was a short-hulled Essex. The Ticonderoga (CV14) was a long-hulled version.
While the waterline length of the ships was the same (820'), the long-hulls had a different shaped bow that resulted in them being 16 feet longer (888' vs 872'). There are also flight deck shape and length differences. You really cannot get to a long-hull from a short hull without major surgery.
I recommend that you check out John Sheridan's Essex class guide on the SteelNavy website for more info
http://www.steelnavy.com/essex_data.htm
As far as aftermarkets to get you to the angle deck -- there are none aviailable now. A long-hulled Essex in 1:350 is on the horizon as the Hancock. Aftermarkets to make the change are sure to follow.
I think I'd watch Nautilus Models for a laser-engraved wooden deck. They also did an Enterprise/Yorktown for the Trump Hornet -- so they would likely be among the first sources for the updated island. James Corley at Nautilus is likely also working on new & different conning towers for the upcoming Revell Gato sub - so aircraft carriers may be somewhat low on the priority list. I know he has the references for the carriers