Did you mean cam on the big side for the factory headed engine?
If you were never gonna switch heads, then yes, you'd need a little larger cam than usual to feed the larger displacement with factory head flow.
However, if you're planning on upgrading the heads, the "good" heads will need a lot less duration to get to the same point. So, you'd need a smaller cam than what you'd think.
From the testing I've done, you gain around 100 rpm of peak hp rpm per 10 cfm that the head flow goes up. If you go from something like a C8AE-H head that flows around 220cfm up to a 330 cfm Trick Flow head, you can see why the cam change would be necessary.
If you stick a set of C8AE-H heads on a 445 short block, with plans to upgrade to TFS heads down the road, I would cam the engine for the TFS heads.
As a rough example to try and illustrate the point better, back in the day when we were using Edelbrock heads, I would get about 475-500hp with a 445 and an Edelbrock head with a good valve job, bowl blend, 11/32" valves, etc. I'd use a 235 @ .050" duration camshaft to get there. When the TFS heads came out, I found that I could make 540-550 hp with them, but use a smaller camshaft at around 230 @ .050" duration. Those Edelbrock heads were about 280-290 cfm, where as the TFS heads sit at around 330. So you could see how much more camshaft you would need to try to get a 445 to work decently with a C8 factory head. As a matter of fact, you'd probably never really be able to add enough camshaft to get them to make horsepower and you could end up with something that didn't have bottom end or top end either one. You'd end up with a huge cam and then when you swapped heads to the TFS heads, you'd end up with something that would be making a ton more horsepower at a much higher rpm than what would be suitable for your application.
Hope that makes more sense.