Is there a take off point on my 893cc Fireblade engine for an oil pressure gauge.

isn't it taken from the oil pressure switch ? You can buy a t piece to connect a pressure switch and a gauge Hellfire have done this on their BEC

I have the 919cc blade I am sure the take off point for the oil pressure switch is this point:



Have highlighted the area. From here it goes to the oil pressure switch and then onto the oil gauge.

Hopefully this helps, but may be able to help a bit more. Do a google search for "microfiche fireblade" or something similar but include 'microfiche' and you may find you can download the file for nowt. Alternatively, look at this website:
Ron Ayers Microfiches