Well, you can resize the Vivace's JBEAM to fit the model. For example, you can estimate how much longer the vivace should be, so the wheelbase fits, than you multiply the Y position of each node by that factor and you'll make it longer JBEAMwise. You can do the same on the width and multiply the x coordinates. Take a look on this tool. It may help you: https://www.beamng.com/threads/nodesnap-new-jbeam-editor.76732/
Its pretty easy to switch it to another vehicle, takes like 20 minutes. I'll check out the jbeam thing but even if I have the jbeam and chassis the right size, I dont know how to do the textures and materials and get the stuff working so I cant continue until Ive got that figured out.
Well, I don't know how to deal with materials and stuff. But the Jbeam is, by far, the hardest process. If you know how to JBEAM, start with that. Probably someone will help you with the materials if you have the car totally JBEAMed and crashing good
Well i have no idea how to jbeam a car and how it works but i'll try out the software you linked. But since its the hardest part, i'll probably wont end well.
The github website is a bit confusing. Not exactly sure how to download the software. Theres a bunch of files but no download button.