SB surgery. Have some ?s

Yes they can be done, though, you will find swinging in the cam very very tight. The post infront of the rad will probably get in the way. But you should be able to swing it in.

The plan of parts is a good one. (Don't like super 40's, just my opinion)

When you replace the timing chain, MP has a timing chain tenteiner (Humm sp!?!?) It will also replace the cam retainer plate, it's designed that way.
A viscous fan maybe?
IMO, I'd use the Chrome box or a MSD or equal ignition.

if you can find a '72 or is it a '73 340 sir cleaner, the one with a trap door cauum operated, get that factory air cleaner. I beileve theres 1 or 2 here for sale. Worth the price. Use a K&N with it. (I'll never get rid of mine!)
Use the Edelbrock thick carb gasket under the carb. OE Carters came this way from the factory to prevent fuel from boiling and overheating the aluminum carb. Very very well worth it!

Make sure you use a break in oil or break in oil additive.