I need help getting my trucks engine running!!

[1968_K20_4x4]

Hey All,

Looking for some help to get my truck running. I recently bought a 1972 K20 with a 307 (I believe it is a marine engine. It says OMC 225 on the valve covers. An internet search told me it is a marine 307, thats about all I know about it). The truck was fixed up about 10 years ago but had been sitting in storage and not running for a couple of years. When I picked the truck up it ran very roughly, and would not stay running, but ran just enough that I could drive it on the trailer if I revved it up. It also smoked like crazy (Thats why I named the truck Smokin Ochre! lol). Once I got it home I checked the oil and noticed that it was quite a bit over full. I drained it to the correct level, and fired the truck up. It ran great! for about a minute, and even idled. Then it quit.

When I tried to restart it, it would crank, fire up to 2-3000 rpms for a couple seconds and oil pressure registers on the guage, and then it dies. I thought it was a fuel problem, so I have since replaced the fuel tank (the old one was stored empty so it was all rusted on the inside). I have also installed a new fuel pump and filter and cleaned the lines. I tried to start the truck, but each time it does the same thing. Fires up, runs for a couple seconds, and then dies. I tried pouring a little bit of gas into the carb and even tried spraying inside the carb with brake cleaner (Saw it on Roadkill...lol!) Whatever I do the truck keeps doing the same thing and will not run for more than 2 or 3 seconds. I have checked the oil level and it is still good.

This is my first attempt at firing up a truck that has been sitting for a couple years, so I could use some help to guide me through what to do next. Thanks in advance! I have added a pic of the truck at the dealer I bought it from and also a pic of my motor. Any help here is appreciated!!