so he is in the group that thinks "it's surviving so it's ok". that attitude wont get anyone far on this forum. your friend sounds like a really intelligent guy btw. i hope you have more sense than your friend and take on board the good advice that will be given.
not only is 60g too small for a frontosa the con is likely to be far more aggressive than it. frontosas can be gentle giants and easily bullied generally. even a firemouth will likely bully a young frontosa.
The GT might be OK, but you might run into problems regardless of stocking when having a pair of fish involved. Breeding pairs generally get really agressive.