i would like to replace them with some after market guages but put them in the origional holes.

i got an oil pressure guage off my mate to see how they would fit. i filed/sanded out the origional holes a bit to make it fit..
this is what it looks like from the back with the guage in..

now here is the problem... because of the pins on the guage seen above the guage does not fit into the origional housing...