there is 2 ways you can do this
the fittings supplied with your autometer gauge is a NPT THREAD
where as the stock supra oil pressure sending unit threads are BSPT
if you want to run you stock oil pressure gauge then you will need a T fitting
or the easiest way to do it since the stock oil pressure gauge lies more then a cheap prostitute on the corner
go get a NPT i believe its a 1/4" tap
you will have to remove accordian hose for turbo with AFM and filter
IIRC i have to manouver my power steering resevoir out of the way
if you look straight down on lower side of block you will see something like this
that is your oil pressure sending unit
its a little tricky to remove it due to the tight clearances
on the lower section of the sending unit there is a spot for a wrench
IIRC its either a 9/16 or 15mm
i used a stubby wrench to remove it
remove stock oil pressure sending unit which is located on passenger side of motor
now take the tap and rethread the hole
use teflon tape or liquid teflon on the threads of the fitting you are going to install
**if you are anal like i am i did not want metal shavings getting into my oil from taping
so i took some wheel bearing grease and applied it to the tap
this way the shaving stay on the tap**
you shouldnt run the plastic hose that is supplied with the gauge cause its will melt due to being very close to exhaust manifold
you can buy the copper tubing from a autoparts store that will work best
be careful not to kink the tubing though
Good luck