Collector flange size for 79 318 exhaust manifolds?

A buddy of mine gave me a free set of exhaust manifolds of his 79 truck.

I put them on my 318 and they fit fine except for the drivers side, had to do some grinding to get it to clear the steering box nicely.

I need the collector flange size so I can install exhaust pipes to them.

I was wondering if anyone knew the size for that? Thanks

Car is a 68 dart