Another piston option for the 273.

I found the existing clearance of valve to cylinder is 0.055
After a 40 over bore and the installation of 1.88in and 1.6ex
To maintain the existing clearance the valves need to be
1.86175in and 1.56ex
That's .040 on the OD of the valves
Really only 20th removal or 0.5 of a mm