Major engine SNAFU! Any advice?

[Scott70Chevy]

I also posted on another site, so you may have already seen this:
My 350 has been running strong, but choke wasn't working (hard to start) and it was sucking gas. Carb had leaks and looked like it needed a rebuild or replacement. So, I bought a reman Q-jet (all new internals, came from Mr. Carburetor in Cedar Hill, I've heard good referals for them). Put it on and it fired up great. Choke worked fine, engine had great sound to it, I could tell it would run like a new truck. A minute later, start to hear some clanking noise. I thought I had left something loose and it was banging something or being hit by the fan. It quickly turned into bad sounding noise (knocking), engine started running rough, and it died. I wish I had immeditately realized something had fallen in the intake! Thing is, I did not have any missing pieces (I think I was pretty methodical during the install). I took the carb back off and did not see anything loose or missing (compared it to the old carb). Now I have three questions:
1). Are there parts in the Q-jet that I can't see through the butterflies that may have fallen out after starting the truck?
2). Does the 350 SBC have an interference fit between valves and piston? (that is, if something held a valve open, would the piston slap the valve?)
3). Before tearing down the engine to check the damage, what am I most likely to find? Is there a chance I (with minimal mechanical experience) will find something I can fix without a ton of dough? Is there reasonable chance it can be fixed with just a new pushrod and valve? Or should I look for a new engine?
Sorry for the long post, but I'm really kicking myself and I don't have the money for a new engine. Thanks!