I assume by 'thumper' cam you mean one with a lopey idle....not a good idea with the low CR setup as it sounds like you are figuring out. Noise does not always equal speed or power. Personally, for the street, I'd look for LSA of 110 or even 112, and duration no more than 262 or 256 range. Lift .500 or less to keep it simple on the springs and valvetrain setup.