307 or 327?

[SS Tim]

Don't do any heavy repairs now, wait 'till things settle down. Remember if it is your first, sleep deprivation is going to be a big part of your life.
Putting a carb and manifold on now is probably not the best thing to do at this point. After all we are not sure what you have as far as displacement or head type. Its temping to toss parts on for sure, but plan it out so you are happy with the results.
If you are not sure of the fluid history then by all means check everything and change as you can in a prioritized manner. Engine oil/filter top the list. Coolant if looks good and tests good can wait some. Auto. trans. fluid/filter again more on condition than a must/now situation. Manual trans and rear, check the levels and look for water. If it looks good top them up till you are ready for a mini project. Example rear axle seals or brakes and cylinders then pull the shafts and look everything over changing the fluid as you go.
Get a service manual factory is great but some people like to start with a Chilton or Haynes first.

[406 Q-ship]

If it runs good then just leave it alone and drive it. Does not matter if it is a 307, 350, or a 327 just as long as it pulls the truck down the road and does it reliabily.