5.0 efi and serpentine conversion.

hello.  I have a new project I am working on.  I have a 67 mustang that I am going to put a 5.0 and aod that I got off ebay out of an 89 mustang.  I want to keep the serpentine belt setup. I am trying to decide the best way to proceed.  as I understand it a late model reverse rotation water pump will not bolt up properly to an early model timing cover, is this correct?  if so then I have two options I buy one of the serpentine conversions from march or zoops, or I use the late model timing cover and drill a hole for the dipstick.  is this correct?  if I drill a hole in the timing cover will one of those after market motorsport dipsticks work properly in it?  or is there a serpentine waterpump that will fit on an early timing cover.  I have the 89 timing cover so I would have to buy an early model timing cover so I think I would prefer to just drill the current timing cover but I am a bit reluctant to do this.  can I get some suggestions from people who have done this conversion?  

AFAIK - yes, drill the 89 cover and stick a stock dip stick in the hole.  
1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.