RARE website shows a modified set that fits 1964-67 GTO !!
https://www.ramairrestoration.com/rm...oversized.html
Pair, New for all 64-67 GTO, LM & Tempests using round port or Edelbrock heads. These require one 2-bolt and one 3-bolt flange (sold seperately). 2.45" collector for more flow.
These are our famous RM-4-OS modified to fit in 66-67 Abody. In the 64-65 Abody you may need to do some minor grinding on rear of underengine xmember to achieve good fit. Many 64-65 customers have also attained excellent fit by relocating engine .250-.500" to rear.
Good luck!