Sounds like a good idea! There are loads of Ghia conversions.I've been interested in ev for a while and now own what I think will make a great conversion.
I have a 74 Karmann Ghia with a bad motor, bad gas tank and body issues that I'm hoping to convert. My plan is to use the EV West kit for its simplicity in installation and then create a diy 18650 based battery system. The design goal is 40-50 miles without killing what little storage space i have available, completely.
I'm here to learn and will probably ask a ton of stupid questions so bear with me.
Building your own battery pack will be tough and probably more expensive than just buying a salvaged pack from an OEM vehicle, but if you want a challenge I guess it makes sense.