A 216 does not have pressurized oil to the rods, so tightening up the clearance there doesn't help oil pressure. It will make the engine run quieter, however. Shoot for .0015"-.002" by removing shims between the rod and cap, and checking the clearance with Plastigauge or shim stock between the rod cap and the crankshaft.
Pulling shims between the main bearing caps and the block will increase oil pressure by minimizing the leakage past the bearings. Again, try for .002" or less if possible. The cam bearings are another story- - - -wear and oil pressure loss there cannot be corrected with shims.
If you have 15 PSI or so at cruise speed with a warmed-up engine, be happy. Some 216's show virtually no oil pressure at hot idle and still run pretty well.
Jerry
