Recommended IA and Navigation Architecture for a single long page scroll?

Website with several pages functioning as a long page scroll determining the optimal navigation architecture. Are there any general usability suggestions for content rich websites with pages designed as a long page scroll? The current ux and proposed ux below. Is it generally recommended to keep main nav items or hide during scroll to focus user attention on landing page nav? I see different sites take different approaches. Current and Proposed UX below in jpeg format for illustration.