I am taking my 263 apart. This car had auto trans so it has hydraulic lifters. The pushrods are hollow to feed the lifters. Do the solid lifter cars have solid pushrods? Also these rocker arm adjusting screws are drilled to oil the pushrods. Are the adjusting screws different for solid lifters as well? I am thinking about switching to solid lifters and camshaft.
My 1950 248 has the same rocker arm adjusters and hollow pushrods as does the hydraulic lifter cars. Some time late 1950 or early 1951, the mechanical lifter engines were changed to no oil hole in the adjuster and push rod. Should work either way.
If you change, the cam SHOULD be reground for solids. The ramps are different. If the cam IS NOT reground, The valve / rocker clearance should be set a lot closer. I believe Dema Elgin said 0.008.