I usually use a small amount of gasket sealer around the pushrod tube holes and the oil drain back hole at the back. This is usually precautionary, but it can't hurt.
Ron L
'73 MkV 750 Roadster
'73 850 Interstate
'75 850 cafe racer
'68 Fastback
'67 P11
'69 Ranger 750
'81 Ducati 900SS
'96 Ducati 900SS SP
'99 BMW R1100RS
'81 BMW R65/Velorex sidecar
'59 Triumph T120 Bonneville