Morning Folks

My 2000 E36 318ti compact has gone through some vast changes over the past 6 months, the engine has been changed over from the standard M44 with aircon and traction control to a 1992 M50b25 non vanos engine and gearbox (82k), non aircon, no traction control, also fitted with a 3.91 ratio LSD from an E30 325i sport, last night I fit an M3 speedometer from a 1995 3.0 car (reason being that the rev gauge doesn't read right matching 4 cylinder clocks to a 6 cylinder engine)

Now heres where my problem comes in, ive checked all the bulbs, I even replaced the newer bulbs from my 4 cylinder clocks and fit them into the M3 ones, but the ABS and airbag light don't come on and go out as they're supposed to (in the UK this is an instant MOT failure), the clocks aren't the issue because the guy I bought them of sent me a pic of them in the car they came from before removal and all symbols were lit up.

The ABS light was on with my previous clocks, I need a rear right sensor replaced, so now to see it not coming up with my new speedometer concerns me, the airbag light has also left me scratching my head, I replaced my standard steering wheel in the car with an ///M sport wheel, the airbag light came on and went out with my other clocks so again I'm unsure as to why its all of a sudden stopped showing.

Has anyone any ideas, ive looked up online some potential causes and some are saying its the differences between the OBD1 & OBD2, the car has a wide range of mods spacing out over 8 years so im worried incase this has caused confusion. Also that the ABS is linked to the ASC and because this is no longer in the car this could be a cause for the ABS light issue.

A lot of head scratching going on lol sorry for the long winded message and I hope most of this makes sense.

Steven