Welcome Helge,
First of all cool car! Looks like a sensible choice especially if you want to keep the original gearbox. Based from own experience space is for batteries is really a struggle, especially if you keep the drive shafts. I got curious about the latest video from ESDI on their T2, the clamp mount for the battery box looks like it will fit anything from T1-T4 including my LT.
Leaf stack should allow for an easy implementation as it has been done so many times but are you running into height constraints or do you plan to split the Motor from the Inverter/Charger part?
What is your use case? For me I identified that I really need fast charging because driving a brick wall around needs a lot of energy. But then a T3 is more compact than an LT.
Battery prices are varying so widely it is crazy. I can share a list of a Seller I used. (I assume you are located in Europe) I bought two BMW iX 111kWh batteries for 2350€ delivered last month) Orion is Popular and well document but pricy. + I was not keen of all the cell taps.
does this work as an adapter for the T3 Syncro?
https://bratindustries.net/product/niss ... apter-kit/ Bratiude is also on the forum.
complexity comes from using anything others have not done yet, so if you keep it to known components have a workspace ready and just need to fabricate brackets and fit it in the car. Than it is actually quite doable. Lastly the only other Motor I can think of is one of the Lexus Hybrid 4x4 but likely not worth the effort to gain minimum space.
Anyways good luck with your project. And remember label bags are your friend when taking a car apart.
Marvin