almost a newbie, but not yet

[DetroitDan]

Hello, I am looking at a 65 GMC 2wd longbed, I want to buy it if the planets align and my Jeep sells this week. In the meantime I thought I'd snoop around and see what I can learn about the truck. Just read 8000 posts about the trucks, mostly just looking at pictures. Came up with a couple questions.

Whats the 305 v6 like in a pickup? I've driven one in an old firetruck (which finally got retired) was a great runner but dreadfully slow. Probably had in excess of 20,000 lbs to carry though. And it wasn't much for shifting either, took a lot of patience. The truck in question has a 3 speed column shift. I'm just curious as to what it will be like to drive. In the future it may see an SBC/4speed auto conversion, but for the time being I'd love to keep it original, as long as I can stand to drive it. I realize it's not a sports car, but I don't like driving things that can't get out of their own way.
Don't get me wrong, I'm not looking for a racetruck, just want to know opinions of the 305s performance.

Truck is on the road now, looks fabulous in pictures. When I travel to look it over, what are some things I should look for; known trouble spots on the frame or anything like that? Mechanical issues that could run to a lot of money? Right now I'm just looking for a local puttin' around truck, not another project. Already got a couple of those I'm trying to work on at the same time.

How different are the Chevys and GMCs? Is it just the grille and tailgate, or would there be a lot involved in converting it to a Chevy? Although I must admit the GMC look is growing on me after looking at a lot of pictures.

Lastly, if someday I wanted to do a big project, is a Suburban or other GM 4x4 chassis anywhere near the same wheelbase?

Thanks in advance for any input. Sorry if my post seems scatterbrained, trying to ask multiple questions at once, probably getting ahead of myself. I usually do.