Sambo - My temp sendor is plugged into the header tank - Got a bung welded in when I had it built- probably not ideal but OK once water is circulating.
Oil pressure I have a sandwhich plate for the remote filter and
oil cooler which had an extra port that I put the sensor into. I have heard of tapping into the domed bit just above where the filter screws in. Think saw that in LS1tech.com - do a little search on there and Im sure you can find a pic.
Cheers