Things to note when installing 1:1.3 ratio rockers:

When you install 1:1.3 rockers, if you’re running a non-stock cam then the angle of the pushrod becomes larger and the slots in the stock guide plate aren’t long enough to support the extra distance required by the angle of the pushrods. 

The best solution is to run an aftermarket billet guide plate which solves the immediate issue of slot length, but then it becomes an issue with the seat height for the studs, so you will also need the modified rocker studs.  If you don’t get the modified studs you’ll most likely end up bending the rocker arms.

This is what we do in our Stage 2 engine which runs the 1:1.3 rocker arms and a 265 cam.

Here are the parts you need:

http://www.cutpriceracing.com.au/store/Guide-Plate-CPR-suit-ENCL65-and-Honda-GX160-200-clones/

http://www.cutpriceracing.com.au/store/Stud-Studs-Modified/