Carl,
You are describing a serious/fatal necessity for only 58-63 261 blocks. They can be identified as having 1/2" NPT oil filter line holes (that were used with the "remote" full-flow oil filter).
The 54-57 261 blocks used optional by-pass (also "remote") oil filters (and smaller diameter diameter lines).
I think that 1958-63 blocks were also available without a full-flow (or, any) oil filter. Those blocks had/have a movable plug to allow no filter, or, move the plug and then require the full-flow filter line.
DFauberWoodsmith,
What year 261? What is the engine serial number in the ledge to the rear of the distributor?
