I agree with you about the quality of the brands mentioned, but I've only built one 250 GTO which happened to be a glue bomb to start. Still, I found this to be a well done kit ... and it does have a beautiful engine! It's not a new kit and available everywhere, so that is probably a factor.
I just wanted to throw another option at you ... the first photos in my build thread give you a good look at the disassembled kit pieces .. http://www.modelcarsmag.com/forums/topic/101568-cannonball-2015-build-ferrari-250-gto-111815-done/?do=edit
(linking doesn't seem to be working this morning)
I'll be looking forward to seeing your build when you decide ..