So I'm in possession of a 1965 Guild F-20. It was my dad's but he doesn't play anymore. It's in pretty rough shape and could maybe use a refretting. Regardless, I like to play it especially for slide guitar, but it is next to impossible to fret notes beyond the 5th fret without them going dead.

Should I invest my money in fixing that up, or should i look to get a new guitar? Any suggestions I don't really have a price range yet so assume its anything <1000$ USD (i have an electric so the need isn't urgent.)

I play blues on the acoustic, if that matters.
Ah, the F-20 is a sweet guitar, it's a shame that it's in poor condition. In this case I would keep that guitar and use it for slide, leave it in an open tuning or something, then look for a guitar when plays properly.
Winner of the 2011 Virginia Guitar Festival

Protools HD
Lynx Aurora 16/HD192
Mojave, Sennheiser, AKG, EV etc mics
Focusrite ISA828 pres
Waves Mercury
Random Rack Gear

65 Deluxe Reverb
American Standard Strat
Taylor 712
Take to a shop and have it looked it. It may only need a good set up, and/or a fret level and crown. That should cost less that $150. If its more involved, they will tell you. Make your decision from there.
--- Joe ---
77 Bradley LPC || 07 PRS CE22 || 11 PRS MC58 Artist || 95/02 Fender Strat || 99 Gibson LP DC Std Lite
06 Ovation Elite-T || 12 Martin GPCPA4
Boss GT100 || Peavey Stereo Chorus 400 || Peavey Bandit 75 || Roland JC77
if you can't get over the 5th fret, could mean a neck reset, but it couldn't hurt to have a luthier let you know what's up.
Quote by Skeet UK
I just looked in my Oxford English Dictionary and under "Acoustic Guitar", there was your Avatar and an email address!