All 3 of those carriers are (fairly) easily converted from existing kits, Mike. The easiest is probably the later CV-6, for which you have a choice of two kits for a foundation: the Revell 1/490 Yorktown-class or Trumpeter 1/350 Hornet. The latter, with its already-modified island, would probably be somewhat easier - though only if you're going to waterline/disregard its bow inaccuracies. For a full-hulled build the Revell would undoubtedly end up being the more accurate.

Converting the Trumpeter 1/350 Lexington (with already-widened flight deck) into a later Sara would be similarly straightforward - now with decently accurate hull, so much less to do, there.

In both cases - Sara and Big-E - conversions would entail as much or more addition/replacement of weapons as anything else.

A Ranger CV-4, however, would be primarily structural mods - though a lot less than you might think, (especially) from the Revell Yorktown mold. If you take a good look at hull plans for Ranger vs the (as-built) Yorktowns, you will see how similar they really were - even the waterline lengths - such that you would get a 480-scale Ranger, when bashing from a 490-scale Yorktown.

That could look pretty spectacular alongside your Revell 480-scale CA (or CL) - equally well for an Operation Torch depiction, or pre-war-exercise mock operations against the Panama Canal. And I know somebody who has all the weapons and planes you would need - whether the F4Fs for Operation Torch, or the pre-war F3Fs, SBCs and TBDs - too!

Cheers,

-Matty