My 65 273 has been sporting a Edelbrock Performer 4bbl intake for 20 years. The difference in the intake bolts is a slightly different angle and the 273 bolts are a smaller diameter. A slight run thru the holes with a 3/8" drill bit in the intake for the mounting bolts holes to slightly adjust the angle was all I needed to do.

I dry fit up will show you what you need to do, if anything.