need oil filter bolt

You might be right, just repeating what my engine builder told me about the plate...some of the newer ones only have 4 holes, the older ones had 6 or more. My builder also told me to forget the 90 degree adapter if at all possible, too many twists and tuns inside it.
His recommendation was one of the "System One" aka "Flying Trashcan" filters, that you can open up and clean.
each to his own...
alan627b