I kept the head on. I used an engine air valve holder to keep the valves in place while I took the spring off. It just keeps the cylinder filled with air while you do the work. Be sure to have a decent size air compressor at hand.
I used a combination of a valve keeper tool to remove the keepers easily. To put them back on, I used a typical valve spring compressor tool. Really wasn’t hard. The keepers are a little finicky and the valve springs are very stout.
Here’s the tools I used.
kweiny Engine Air Valve Holder...
Amazon product ASIN B07FYCSKJV
Lisle 36050 Valve Keeper Remover and Installer Kit
https://a.co/d/4n4K1CP
ATPEAM Overhead Valve Spring Compressor | Universal Automotive Engine Removal Repair Install Tool
https://a.co/d/jfBXlRR