ALL 502's have forged cranks, forged pistons, and at LEAST 7/16" GM forged rods (newer 500/525's have custom Merc Racing rods).

Performance:

502 +

500 ++

525 +++

So would running a 500efi or 525efi cam be too much for my 502?
I do have cmi etops but otherwise pretty stock until I put the sidemount whipple on.

The simple answer is no, its a great cam. With different heads and some other changes that cam (525efi) lives in a lot of 600++ HP engines.

The more complex one is that you would till need reprogramming etc to the 502. You can't just do a cam change on any efi engine, and not change the computer

I will be re-programming the whole system anyway when I put the whipple on, so that won't be an issue. I wasn't sure if the stock 502 heads would be okay with the more aggressive cam of say a 525.

They will be fine. HP is going to get you in the range of ~500.

Keep in mind that you are going to need to change the rocker arms to adjustable ones, the push rods, and the lifters