For the oil pressure gauge - Do not use a t-tap at the block. DON'T.
You have 2 options.
1) You can get rid of the stock switch style (you will have a light on your dash, or you can remove it, or jumper the stock wire...) and use an aftermarket sending unit with adapter (as long as it isn't too long/heavy) and just go that direction. (this is the far cheaper option)
2) If you want to retain the stock pressure switch (it is not integrated with the ECU, it doesn't care) then you will need to do the following if you want to ensure nothing breaks off and you lose all of your oil (yes, it can and will happen).
Get a stainless line built that runs from the block to where you want/wish to mount your sensors (as MR2Jedi indicated), adapt the block oil pressure port to the stainless line - then at the other end of the stainless end, put your T-Tap and secure it to something solid that doesn't move.
the 4afe holds the pressure sending unit parallel to the ground - adding a t-tap with even the stock switch and a line is too heavy, and it will break through vibration - which will put your oil pressure open - and you will lose massive oil, quickly.