Rune,
Don't know anything about small blocks. Having said that:
On my 460 there's a tapped hole just above the mechanical fuel pump location on the front driver's side of the block. This hole leads to the output side (gallery) of the
oil pump, so that's where I put mine.
Also on the 460, there's another place on the top rear center of the block where the
oil pressure gauge fits. Some have used that spot and report it works, too, although I've not personally seen it done.
As a third option, if you have a remote filter and/or an
oil cooler, Canton has a schematic for you to use to tee into that line.
Finally, there's another option, also I think from Canton, to put an adapter between the filter and the block to accept the output of the Accusump.
I don't know of anyone using the check valve. Maybe someone else can contribute some experience.
A very big caution: don't install the Accusump piping incorrectly! It's easy to overthink this and plumb it in backwards, resulting in no oil pressure.
Hope this helps,
Tom