You’re a plonker.
This forum has rules, and personal insults/name calling fall foul of them. :nono:
If you must criticise, then criticise the behaviour, not the person.
I'd agree that fitting a non-conforming steering wheel without an airbag to a 500 intended for road use in the UK is an ill-advised thing to do. Since this is a public forum, visible to anyone with an internet connection, it's only right and proper to point out the possible consequences of doing this, in case someone else is tempted to make a similar modification.
Fitting a part which renders the car unroadworthy (and the MOT rules are quite clear about this) will almost certainly invalidate any insurance. In the worst case, if the car is involved in a fatal accident, then a prosecution for causing death whilst driving uninsured is a very real possibility, and likely to lead to a significant custodial sentence. The police investigation following a fatal accident is extremely thorough, and this thread could be produced by them in Court to counter any possible plea of ignorance of the law as a defence.
But if the OP decides to proceed with this in spite of what's been said, then that's their personal choice, and I respect that.