You can get by with just changing the pump which keeps the tcover/block hole orientation as is & functioning but it causes a slight aforementioned prob reading the timing marks. If this was a permanent deal then yes I would want to swap covers & remark the dampener to match and there was a bolt on tab on some 60's SB's (they're available used) that went on the pass side (I have one) & if it bolts onto the late tcover that'd take care of the dampener markings other than a white paint mark for TDC