I like using 7/16 pushrods if they fit. Not so sure they'll fit on a TF head without grinding though. A 3/8 pushrod should fit. The dual taper is nice but expensive. Another option is the Smith Bros or Manton style where the pushrod body is straight but then they use long ends with a taper that provide extra clearance. The nice thing about that style of pushrod is that down the road you can have them cut down and put different ends in them. The dual taper pushrods can't be remade into a different length so you have to buy new ones again.