I really want a G1 styled Jazz for my display, can anyone suggest a possible way of converting Animated Jazz into a more G1 style?

Not really. Animated is way too unique in its aesthetics to work as a Classics toy. His altmode doesn't work, his arms don't work, his waist doesn't work, etc..
You could do what I did and modify Botcon 2008 Jazz into G1 Jazz, but that's costly (Jazz, to me, was worth it, though). Or you can get some modeling compound, some Gundam fists, a Target G1-ized Movie Jazz and mold him on some extra armor plating to give him a more G1 set of aesthetics.