That's an interesting conversion.
First call would be the people who converted it in the first place.
For custom mapping,Rick at Unicorn would be your best bet,but what exactly do you want to get from the car,as that will help you decide what you need.
I was going to say Tsr performance but there in Somerset so a bit of a drive for you mate
Yeh that's Abit far.
What did you get done from them.