A returner, rather than new...

Having spent a few years divorced from the MTB scene, thanks to my Scott Genius and Giant being stolen, I've finally scraped together a few pence and got myself a project - the Orange 5 that I always wanted but could never afford.
It's something of a bitsa, and needs plenty of love and attention, but I'm back and looking forward to hitting the trails.
A few questions though. I've always really enjoyed trail centres, and have been happy to hike-a-bike up the climbs (mainly thanks to being unfit!) so was considering a 1x9 (or similar) conversion to simplify things. No point in having 3 billion gears if I never use them... is it worthwhile? Also, my 5 is a really early one (the one with the straight top tube, not kinked), and I'm unsure of the original spec, so am thinking that I may need to / could upgrade parts from those that are fitted, if I actually knew whether the parts on it are the original spec of lower (they don't look to be higher...)
Early Orange 5, Felt Z85, Scott Thicko, modified Giant full suss (both nicked)- beat-up single-speed rigid 1992 Saracen (scrapped), and various 2-wheelers with big engines