Greetings from Australia

Hi from NZ.

My advice would be to disregard the technical aspect at this point and find how to make a profitable business model first off- if you are intending to do this for a living. It is not an easy business model, one fraught with pitfalls and traps for young players. The biggest trap is thinking it will be profitable. The second biggest trap is thinking it is going to change the world/improve it/save it etc.

There are a few existing players who have been in business for decades, they are surviving but I'd very much doubt that they are listing on the share market any time soon. As a newcomer, you'll have to do all that they are doing and then do it better, all without the resources, reputation and customer base they have. A bespoke retrofit business model is somewhat linear in that the amount of work you have to do on the first one is almost the same as the amount of work you have to do on the Nth one. While you can reduce costs a little with bulk buying and manufacturing, there isn't much non-linearity in the scale factor so you are in for a hard slog. Your profit is in your value-add, if all you are adding is installing somebody else's equipment into a car and giving it a shakedown run then that isn't a lot of value for the amount of effort. Not impossible, but there are easier ones out there.

For the technical side, get a degree, or other relevant trade qualification. If you are putting customers lives in the hands of your engineering skills then a two week course at some guys workshop isn't going to cut it. I used to play around with motors and wires and stuff as a hobby 20 years ago and somebody told me to go get a degree. I didn't really go to high school so it was a bit of a battle but finished a BE Mechatronics at 32yo and have had a great career as a contractor since. Best advice ever was "the most expensive thing you can do with your life is stay in a low paid job".

Would I start an EV conversion shop? No, I couldn't afford to. Possibly not the advice you want to hear, but if you can find a business model that is profitable then more power to you.

Do you offer a warranty? That's one that'll catch you out if your not careful. Just imagine a customer comes in and pays you 40K for a drive in/drive out conversion and 6 months later the battery dies?
That's potentially another $20k for the replacement. If you don't at least try to sort something out, the reputation from that would kill any credibility you had.
That's what happened with this build for a customer,

Anyways, My suggestion, If you want to do conversions as a workshop to the general public, Make a workshop car. Convert the parts chaser to electric and the experience and knowledge you'll get from that will be invaluable. Its only just been Chrismas break and recent lockdown/work from home restrictions have changed the way a lot of things are going, that's probably got a lot to do with why you haven't got an email reply yet, They may have only went back to work a few days ago.

It is potentially a booming market, but it'll be similar to what happened with the horses when the car came along. Most horses were replaced but the ones that still remain and the people who are really into them, that's a niche market with a small, but generally wealthy customer. The same will happen with cars, most people will just upgrade to whatever new car is available at the time, or just sign up to a subscription service once full autonomous arrives. The few left will spend absurd amounts on high quality conversions because that's just the cost to play, but they'll probably also want expensive classic cars and other cool things.That is still a while away, maybe 20 years? Until that point, its still realistically going to cost $40-60k to do a proper conversion, most people will just buy a new car and the ones like us will be figuring out how to do it ourselves to save some of that money. Qualification wise, you want to be a mechanic obviously, with good knowledge in electrical systems, wiring diagrams, circuits, electronics and have done a HV course. It would be absolutely ideal if you were a mechanical engineer, with approval from RTA to sign off on vehicles, Otherwise your shop will need to be working closely with an engineer, to ensure they are happy with the work you do and that you follow the rules and ADR's so it can pass at the end.