The manifold should work. My stock manifolds (intake and exhaust) from
the 305 are now on the 350.
The Quadrajet can be a great carb when it's not worn out and is
adjusted properly. A lot of people like them for their
"off-roadability" when climbing steep hills or being at odd angles.
They apparently work better than most carbs in that aspect. Knowing
what I know now, I should've rebuilt (or had someone rebuild) my
Quadrajet rather than go aftermarket. I wasn't trying to build a
high-performance engine, just a good solid street engine that would get
me there and be able to tow when required.
If you're thinking of installing that 350, I'd make sure to test all
the usual stuff like compression. Check the oil in the 350 for any
weirdness, like particles of metal that would indicate heavy wear of
parts, etc... Basically inspect everything you can before removing it.
I'd replace all the gaskets while it was out of the truck. Gaskets
aren't terribly expensive but can be a real pain later if they decide
to go out on you. And if it doesn't compress well I'd go ahead and do
a ring job while it was out and apart. Again, not a huge expense if
you can DIY. Make sure you've got a good torque wrench.
Reconnecting all the factory emissions control equipment would help
ensure that it still passes inspection.
If you have the space and a little help from a friend (to pull the
engine and get it on a stand) you could probably have the engine
inspected, removed, torn down, gaskets replaced and back together in a
few evenings. Then I'd allot a weekend to get the 305 out and the 350
into the Blazer.
Unfortunately for me, I live in an apartment (gated community) in
Midtown Atlanta, GA. So I'm unable to do any real work here at home.
Because of that I've lately been wondering if there's any local Chevy
truck clubs where people can get together and work on each others
vehicles and "talk shop".
Good luck to you... This is a pretty good forum for picking up tips.
I've learned a lot by just reading posts and not necessarily asking