1970 455 Timing cover oil passage

I have a 1970 455 block and have had the oil passage drilled out to 5/8. My question is with the timing cover, I have the TA booster plate to install but do I need to enlarge the hole in the timing cover? Does the 71 and up have the larger hole already, if I can find a good used one?

 

http://www.trishieldperf.com/455_block_mods.htm

Jim Weise's multi-page write up on oil mods for the BBB.

hrn. just read through that and it doesn't seem to address the timing cover question at all. o No:

 

http://www.buickperformance.com/oilflow.htm

George Nenadovich covers the timing covers (heh).