is this a good topend for a 347

I'm guessing the 1420 is just the model number for afr 185's?

If you are dropping the money on the afrs, might as well get a custom cam.
You may also want to do a spring upgrade.

I see no mention of a new intake, consider a victor jr efi.
The cobra is definitely undersized, ported or not.

I'm not overly familiar with those valvetrain parts, just check reviews to make sure the brands are a good quality.

You are going to need to have the maf recal'ed and get some 30's. Yes, 30's will work in a NA situation. You do NOT need more without a supercharger, regardless of what these guys tell you based on ratings and charts.