Found these rings (I think for VW) but are the same spec as the B5234T rings.

Brand Sealed Power
Manufacturer's Part Number ZE494K
Part Type Piston Rings
Product Line Sealed Power Performance Piston Ring Sets
Summit Racing Part Number SLP-E-494K
UPC 087674939126

Bore (in) 3.189 in.
Bore (mm) 81.000mm
Top Ring Included Yes
Top Ring Thickness 1.5mm
Second Ring Included Yes
Second Ring Thickness 1.75mm
Oil Ring Included Yes
Oil Ring Thickness 3.0mm
Oil Ring Tension Standard
File Fit No
Gapless No
Top Ring Material Iron
Top Ring Facing Material Moly
Second Ring Material Iron
Second Ring Facing Material Cast iron
Oil Ring Material Chrome plated carbon steel
Quantity Sold as a set.

These appear to be the same spec as the stock rings in the motor. The difference being they are only $74 for a set of 4 cylinders. The stock rings I have found are like $54 PER Cylinder. I can buy two 4 cylinder sets and have extras if I run into an issue.

 

Just call and ask for Sealed Power ring set for your Volvo; a good common brand that many folks carry or can get. Or Mahle, which is likely the brand pistons that you have.
You can't mix brands in this situation.
Figure out what you have FIRST, then get what you need.
Ed

 

I would also contact VMS, they used to sell Ross Moly ring sets for the 850...

 

I have actually found a set of Total seal rings for the stock pistons for $210 with a gapless second ring. They are same specs as stock rings and use a gapless second ring and improved oil ring design. Gonna run with those as they are in between the price of the others and stock.

 

What other parts were you considering over stock for your rebuild? I'm curious because I plan on the same rebuild in a few months.