The Severn Valley Railway has been released by Steam Sounds Supreme for Free. https://www.steamsoundssupreme.com/severn-valley-railway The manual is on that page - have a read as there is a big list of Payware routes required Not sure how many assets are required from each payware route.
I took a punt and installed it missing the marketplace payware and also missing Portsmouth Direct (although I have the newer Portsmouth-Waterloo) & Falmouth Branch. Having just done a quick blast end to end I didn't notice anything alarming missing or weird (a bit of levitating hedge 4 miles from Bridgnorth and that was about it). As you allude to though, I really wish more would state what is a deal breaker v nice to have for dependencies. Its a right pain for some routes, especially as a lot of the freeware dependencies are hard to get hold of since UKTS vanished. I should also add that the NNR high detail route they've also recently published is a significant improvement over the JT original.
