1968 318 to 1973 340 water pump interchange

I ended up swapping just the water pump and left the timing cover alone so that timing marks are still correct with the damper. This did require swapping the alternator brackets also, but then everything else is left alone. I will be putting a 998 style transmission with lockup and lower 1st gear ratio behind the 340. I have a B&M weighted flex plate to go with the externally balanced 340. When I called B&M they said it was discontinued, and no replacement. But thanks to ABodies only forum I found a thread that informed me that the 727 weighted flex plate has holes in it for a 904 also. I had called TCI and they said they did not have one either. Mabe theirs has two sets of holes like B&M's.
I just bought 1 off E Bay made by Hays for $54 including shipping. For external balanced 340 w/ both sets of holes for 727 or 904. Put it in this past weekend. No vibrations. It had a small vibration before because of neutral balanced convertor and stock flex plate.