Wow that’s very nice. I bet it has a great dry woody crispy tone, and light. It’s a ‘58 for sure Because it has maple back and sides. The F20 went to a mahogany body in ‘59-60 and on after I believe. Though the maple back and sides were normal stained a dark red like mahogany, yours may have been refinished natural. Looks nice. I have a ‘72 Guild that was refinished that way, no stain. Looks like it’s had some desirable upgrades. These early Guild bridges had slide in (glue in saddles) which not very convenient. To service the saddle you had to break loose the glue, sometimes cracking the bone. It is not uncommon for these early guitars to be retrofitted by folks with easier drop in saddles like today. The smaller teardrop Pickguard was changed out for the newer contemporary shape which is fine, I like the dark ”tortoise brown” color choice. Action is nice and low, tall saddle. Looks like a neck reset might’ve been done, looks like a very thin spruce shim under the fretboard over the body, but hard to tell in the photo. I’ve got some with the same shim. All in all it’s in fantastic condition with a lot of life. Be proud to own it.