Hello Richie. I have 072 curves and find the 21” cars too big for them, let alone my smaller loops. I’ve paired my Legacy engines with 18” MTH passenger cars and really like them. Maybe that could be an option for you. Admittedly, colors could be an issue unless you go all silver.
As an aside, I think a Legacy E8 would be really big for 036 or 048 curves even if it actually navigates on them. Also, a 15” car might seem small and overly compressed behind either the Legacy PA or E8. My $0.02 worth (and maybe not worth that).