You don't have to drill anything. As for the pushrods, I don't recall the exact size you need, but I purchased mine directly from Trick Flow. They are TFS harden pushrods. The exact length is stated in the directions that come with the heads. Someone here probably knows off the top of their head. Anyone?
The TFS TW heads are really nice. Are considering getting them? If so, I would recommend a very mild clean up on them - no heavy porting. However, if you are planning on a blower/nitrous, then I would speak with a reputable CNC shop about how much porting you need.
Good luck!
