My research shows 1963 has different angle for intake bolts, however 64-65 has same as 318 up to magnum heads, 90 something. I have marine single plane for sale.
No it doesn't. No 273 in 63. 64 and 65 have the goofy angle and the smaller bolts. 66 and newer up to Magnum has the same bolts and angle. Your marine manifold may bolt on to a 66 and up heads from what I gather from your part number
(late 60's) but I wouldn't recommend it.