Update....Success! Tried all the methods suggested except ultrasound. Was tired of messing with it and was about to get more aggressive. Sprayed it with Gumout every 10 minutes for a day (evaporates quickly), next day, free. Everything looks good, clean it up, stick a kit in it. Probably never use it, stick it on the shelf, wife will sell it at the auction for 5 bucks.
MeanGene, you have a message.

Thanks guys for the input. My primary concern with the 347 setup is or was with the rod angularity but it sounds as though it works. I'm with you as to we'd rather have the FE. We looked at one Cobra advertised as a 427 but no matter how I looked with my flash light you couldn't see the cross bolts. We had them put the car on the hoist and sure enough...no cross bolts! Probably a 428 7 liter with a med. riser two four intake. It idled so smooth! Who ever bolted it together was not a FE man...oil leaks every where.

So what was the outcome.   Looking to take a 390 to 410.   

are you takling stock or hot rod?where are you located?

I've built more 347's/363's than I can remember.   I have no qualms with the 347 and have only built one 331 in my lifetime as an engine builder.   I did a 347 for a local bracket racer.  He ran it for 8 years in a local 7.50 1/8th mile class, while driving it on the street.   I took it in for a freshen-up and the cylinders/pistons looked great. 

One of my journalist friends from Muscle Mustangs & Fast Fords had a Fox Mustang with a 347 in it.  Had 100k miles on it. 

You can only believe about 10% of the stuff you read on the internet, but Randy Gillis did tell me that Probe Pistons really messed up the design for the pistons when the 347's started coming out.  Led to lots of oil consumption.  You just don't see that anymore.