Biggest Cam in a 360?

The Comp Thumpr series is designed to sound like you have more cam than you really do. Or, if you want to look at it the other way, all the bad manners of a big cam without the power.

Somebody mentioned the MP .509 cam. It will certainly have a rough idle but will make good power too assuming you have the compression. Since you say stock bore so I'll assume stock compression.

If it were me, I'd rebuild the short block with KB 107 pistons and an XE274 cam. With factory compression the XE268 might actually be faster.