[Yendor]

I think I'd be worried about trying to repair the crack in the upper case where the cylinder jugs sit. That was caused by the Bearing Alingment Pin NOT being seated in the Hole for the Bearing Race when the Cases were assembled. The Pin was pushed Up and crack out the Side Wall of the case - No Place else to go.

The Crack on the Oil Windage Plate can be welede but you will have to drill out the tops of the points where it is riveted in place then drill and Tap for Bolts.

If you decide to attempt a repair on the upper case here's how I would go about it.

Pry out the chips that are broken out.
CLEAN - CLEAN - CLEAN
Pull the Alignment Pin out.
Assemble the Case halves with the Alignment Pin in the Bearing Race.
Make sure the Pin is fully seated in the Bearing Race (from the look of the crack you should be able to push it down once the chips are removed).
Have someone TIG Over the Pin and Fill In Most of what was removed from the chips. The TIG won't stick if it's not cleaned properly. But also should not Weld to the Pin as the Temp Required for the Aluminium should be low enough.
Take a Dremel Grinder to clean up the are and make sure the Clinder Jugs seat correctly.

I know this will work as I had a similar issue with a Pin on the transmission shaft and that's how we fixed it.

Or Just pick up a case set on Ebay. All CB & CL Cases are the same for 350's. The early SL will also work the later ones were Kick Start ONLY.

 

[Yendor]

99.9999......% Someone has been there before you. It's very unlikely the factory made that error.

 

[Yendor]

Bar Keepers Friend is just Oxalic Acid mixed with a little scouring powder.

If you are soaking the parts just go right for the Oxalic Acid - it can be found at most hardware stores (but Not Lowes or Home Depot) - Sold under the name of Wood Bleach. I found it at Ace Hardware.
[attachment=0:90jvc2sr]WoodBleach.jpg[/attachment:90jvc2sr]

Here an On-Line Link:

http://www.hardwareworld.com/Wood-Bleac ... 4Aodg0wAxw