I'd start by talking to Richard Morgan or Graham Swann - oh wait, I already have!
*1 from
http://www.electricclassiccars.co.uk/ 'cos they're good at this.
Seriously though, I only talked to Graham about this for about 15 minutes, but be gave me (
me!) confidence that this is eminently doable, whether using Lead/Acid or Li/Ion (from memory, he's used the latter).
He's really approachable, and is doing this because he wants to, not because he wants to build a massive profitable conversion business, so I'm sure he'd be pretty open with his advice.
One of the really beauties of EV propulsion is it's simplicity - it must be easier than some of the projects attempted on here!
I'd be happy to pick up the 'phone to him, if that helps you Goran.
*1 at this in September:
https://www.eventbrite.co.uk/e/elect...s-24715554890#