1965 273 4 bbl intake

I would not go that route. The 64 & 65 273 heads use a 5/16 bolt with a 1/2 wrench. It is also at a different angle. I am sure people have done it but I could never recommend it. The 66 up 273, 318, 340, and 360 use 3/8 bolt at 90 degrees to the intake face. It will be easier and probably cheaper to get the right intake.