I have an aftermarket ATS turbo in my 87 6.9 and I had problems getting at the stock sender. I put a T into the oil supply line to the turbo. Its very accessible. I put in another T for a Napa sending unit. The stock wire just reaches to it. Instead of close nipples I used air compressor fittings. They are short but have a hex center so you can tighten them.
Mike