Thanks KP. 

I got a laugh out of this one.  Seems you could get your hands on what looks to me like a sandcast mirror.  Catch is you have to buy the GS750 attached to it. 

http://www.ebay.com/itm/Suzuki-GS750-GS-750-motorcycle-parts-1977-1978-/122043805364?hash=item1c6a60aeb4:g:aGMAAOSw0kNXhUqn&vxp=mtr

I'm sure the seller would have no idea why someone would want this mirror if he was asked. 

Looks a bit too crusty for me to be interested. 

I knew I wasn't crazy.  I was picking a junk yard years back and stumbled on a Honda 450 with a rolled edge rim on the back.  It had wheel weight holes in it and I wasn't sure enough of the exact dimensions I would be looking for so I left it and went inside to pick the shelf bins. 

Scouring e-bay this morning I found this auction.  Sure enough it's a rolled edge rim with wheel weights.  The seller thinks it's a 19" wheel and I'm assuming he's right.  Perhaps another model had the correct 18" wheel on it?  Sure would be nice to find such a unicorn even if one had to weld up the wheel weight holes to make it work.

 http://www.ebay.com/itm/Honda-SL350-1970-Rear-Wheel-and-Sprocket-19-/231989277764?hash=item3603a37444:g:sWoAAOSwADNXPL9Y&vxp=mtr

I have the Yamiya's.  The Philips slots are huge compared to originals.  Would rather have ones that I need to restore over the Yamiya's.  

Took me three years to find all the right #8 bolts,  I'm not about to let the seat screws be wrong.  

I don't think these things are rare but it sure is turning out to be a difficult quest to find them.


Thanks for the offer Tango but it looks like someone put a later strap on that seat.  

Attached is a photo of the one original screw I have vs. my seat with the Yamiya hardware installed.

Fortunately I have the rest of the hardware for re-chroming as I think polishing the tool marks out of those stainless brackets would also be a waste of time.  

The seat cover from Yamiya is second to none but I sure wish they had more accurate bits for the finishing touches.  I suppose this would make their parts require even more saving up than present though. 
    

This mirrors is a scam...  Well, at least the seller is wrong and doesn't know it.  be aware of HM PAT logo mirrors that have the stem too far off center.  If the HM is residing in a narrower space than would be expected on any CB750 that's because it came from a much smaller CC machine.  http://www.ebay.com/itm/121592265410?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

http://www.rivetsinstock.com/rivets/solid-rivets/small-solid-rivets/round-head-solid-rivets.html

Here's where I'm going to try to get some rivets.  I'll check the dimensions and compare them to the closest they have and see if I can get some in stainless from their sales office.  I may end up buying a hundred just to get the four I need. 

I have a dozen new screws for the stay brackets.  They have a tiny x in them as compared to the original dot and are slightly long though.  This is what is available from the dealer these days.   

I bet Vic would be a wealth of knowledge on this subject.  I'd work on establishing a long term dialog with him before picking his brain right out.  Might take years. 

http://www.ebay.com/itm/Honda-CB-1969-cb-750-tested-running-sand-cast-motor-with-working-4-cable-carburetors-/251636090981?forcerrptr=true&hash=item3a96ae0865&item=251636090981&pt=US_motorcycles

I only see 6 later SC engines than this one in our directory.  I'd take a stab at less than a couple dozen in existence perhaps. 

Not sure stamping numbers on an un-numbered set is the way to go.   They are obviously replacement cases and may have some later differences than the very early cases that would be correct for your sandcast.  They will have date codes on the back that will date them to when they were produced and verify that the top and bottom are a matched set.  Placing numbers on them that are earlier than the production date would really raise a red flag.  

Not that I've never thought of doing something like this.  I just realize that once it's done you can't un do it.  

The value of an un-stamped set of sandcast cases is a bit less than ones with a vin on them.  The value of your sandcast is considerably higher though as you are in the three digit vin club.  

One of your baffles is definitely later/non lotus root.  Compare the height of the external seams on the mufflers and internal supporting to verify that one of the mufflers is in fact non lotus root as well.  I'd wager it is but I'd also check.