Just set up cylinder #1 as if it was a 273... Use the 273 solid lifter, 273 push rod, and 273 adjustable rocker arm and adjust to zero lash... Just do that for the one cylinder to check everything and then put the proper roller parts parts back on when you are done...
The 273 parts will be correct to measure the lobe, a lobe is a lobe, approximately .500" lift and 240 - 300 duration...
