If you want to convert your site from RSD 1.5, why not try Vanilla in SD3? You can do it desktop down. But still, 63 pages is a lot.
I was looking at Vanilla in V3 it is CSS (no framework) so from what I have read I have to actually start from scratch and add code and not being a web designer like you and so many others here on CC that is something I won't even try.
Most likely I will just redo from scratch the site now have to decide on RFF or take the plunge and use SDV3. If I don't have to worry about that grid thing and use only flex and not worry about the IE-11 Fallback it is something to reconsider.
it may take time BUT as long I can get it redone and running by end of summer. In the meantime will keep the site up in 1.5 as the saying goes " If it ain't broke don't fix it"
Ray aka Kreations
Since 1994 Chocolate bar wrappers for all occasions.
Since 1972 helping clients help "Discover Their Dream Vacation"