DB2 to DB4 Purolator (Pure Oil Later) oil filter head on an exchange basis only, this actually fits all up to but not including DB5 engines, normally supplied the oil pressure differential valve removed & blanked off (this valve came into operation if the oil filter gets blocked by lack of oil changes !) oil will only actually flow through the filter and not open the valve (because there isn't one !) when the oil is cold,  so just keep changing the oil filters regularly, we also modify the head to align the oilways with the adaptor / block.

This is how we build our engines.

We keep all of the filter bowl parts & the head to adaptor or block gasket which has been modified slightly for a better fit.