My take on the oiling system crossover tube for the small block

If you are trying to achieve the desired "straight through" oil passage that is line of sight from the main to the rod, there isn't a lot of leeway either direction to maintain that. Changing timing beyond that requires an angle drilled "L" passage or crossdrilling. Especially if the journal has a lightening hole.

It comes back to a full groove (bearing set or in the bore) to provide 360* oil on the rod if that's deemed necessary. Or less depending on the balance between surface area and oil needed.

Engine oil pressure is not what creates the hydrodynamic wedge anyway (as opposed to hydrostatic lubrication), so is it really necessary to have 360 degree pressurized oiling as opposed to just making sure it gets what is needed? How do we know what is needed? Observation - i.e. watch the filter as a problem will show up there first, take it apart and check it, fix it and make a change or adjustment. Rinse and repeat until you get results. The trick is to work the process without blowing the thing up.

Oil Clearance and Engine Bearings [SubsTech]