Need Help IDing a 4 into 1

[crazyramen]

Howdy y'all I just bought this 4 into 2 into 1 header thinking I got a good deal for ~$100 shipped, but it's not fitting on my '79 750. The flanges have too tight of a bolt spacing, and the top of the collector where 1 and 2 connect hits the oil filter cover. The outlet would also run into the center stand with a muffler attached, but I assume a lot of racing oriented pipes are like that.

I've taken some measurements and I'm thinking this might've been attached to a cylinder head from a smaller displacement model and wanna see if any of you smart folks can help me figure it out - hopefully I can get it to somebody that can use it.

Here's the original listing: https://www.ebay.com/itm/136843452212
There is a model number stamped into the collector SU768SSH 8-99, but nothing came up in a google search for it.

The cylinder head it came off of is painted black, but I can't tell if that's original: https://www.ebay.com/itm/136846239372?_trksid=p4375194.c102726.m162918

Pics of it "installed" on my '79 GS750: https://imgur.com/a/ebay-4-into-1-NUK0DCE

Here are the measurements I took: [TABLE="border: 1, cellpadding: 1"]
[TR]
[TD] [/TD]
[TD]OEM 1979 GS750[/TD]
[TD]Ebay 4into1[/TD]
[/TR]
[TR]
[TD]Flange into cylinder head[/TD]
[TD]OD - 45mm
ID - 32mm
Depth - 19.5mm[/TD]
[TD]OD - 41.5mm
ID - 35.5mm
Depth - 16mm[/TD]
[/TR]
[TR]
[TD]Mounting Clamp Hole Spacing
(center to center)[/TD]
[TD]60.5mm[/TD]
[TD]57.5mm[/TD]
[/TR]
[TR]
[TD]Pipe OD[/TD]
[TD]39mm[/TD]
[TD]39mm[/TD]
[/TR]
[TR]
[TD]Mounting Bolt Hole[/TD]
[TD]8mm[/TD]
[TD]8mm[/TD]
[/TR]
[/TABLE]
The output pipe diameter is 50.5mm/1.98in

Any insight is greatly appreciated

 

[first timer]

it's likely for a oil or liquid cooled gsxr 1988+

 

[crazyramen]

it's likely for a oil or liquid cooled gsxr 1988+

The thing that really throws me off is that the head they pulled it from is an 8 valve

 

[first timer]

The thing that really throws me off is that the head they pulled it from is an 8 valve

Do you have a picture of that?

 

[crazyramen]

Here's one of the pics from the ebay listing

https://www.ebay.com/itm/13684623937...102726.m162918​

 

[uk gs nut]

Looks like a 750 or 850 head, there are mounts for idler pulley between cams.

 

[crazyramen]

Looks like a 750 or 850 head, there are mounts for idler pulley between cams.

Maybe they were running a smaller cylinder to get higher compression so they didn't have the clearance issue I'm having with the bottom of the engine?

I'm getting kind suspicious that it actually came off that head. I can't imagine that the bolt spacing would be different for the same displacement and era and those exhaust ports don't look modified to me.