Newbie thinking about diving into a '65 GMC 1000

[Praxiss454]

Hi all,
Lurked here for a bit, and figured I should register. A bit about me: always done my own maintenance, and have done some tuneups on naturally aspirated motorcycle engines, but have never taken on any kind of project like a 50+ yr old truck.

I'm considering buying a 1965 GMC pickup from a colleague who acquired it as part of an estate and doesn't know much about the history. According to the VIN, it is a 1965 GMC 1000 with an inline engine (guessing a 230?) with the 115" wheelbase, built in Fremont, CA and a GVW <6000 lbs.

From the pics it looks like the interior is in rough shape, but the body appears to be in pretty good shape. The door jamb is a red/orange color, but the exterior of the truck is white so I'm guessing it was repainted at least once. I have not actually seen the truck in person yet, going out there this weekend. My purpose for this truck would be just a hobby truck to tinker with, fix up a bit, and turn into a daily driver around town or to the beach. Nothing too fancy, and not a full restoration.

Here's what I know:
1. all 4 tires are flat and won't hold air
2. appears to be missing ignition cylinder, which was possibly replaced with a push button start. Also no battery
3. colleague says seals around the glass are in decent shape
4. no major rust holes visible inside or out but hasn't been scrutinized
5. It was registered up until 2012, when it was then registered as non-operating
6. Registration has been updated by current owner and is up to date (non-op)

Here's what I don't know:
1. When was the last time it started up?
2. Is the engine seized up?
3. Is the transmission functional?

Questions I'm hoping folks on this board can answer:
1. Do you see any glaring red flags from the images I've posted?
2. Are there any obvious modifications or other non-standard things about this truck? (e.g. does the engine look right, the bed look right?)
3. Specifically, are the grill and the tail fender of the truck stock?
4. What do you think it's worth, given the knowns and unknowns? Would you call me crazy if I paid $500? $1000? $1500? etc

Thanks all for reading, and looking forward to hearing your responses and getting to know ya.