+30 piston rings: available or not?

[Philippe-J.]

My 4.2 l engine was rebored to +.030 thou in the past. I found the cylinders in very good condition, as the pistons, so decided just to change the rings. I wanted to keep away form the ultimate grinding (+0.040) if not resleeving. Alas, it seems difficult to find +0.03 rings, if not impossible.
SNG has the FZ60130 reference, sold per unit. This is not an issue to me, I just have to buy 6 of them

They are said "+0.03" but it is not clearly stated for what engine they are, so I bought only one kit just to check.
I found that I have to slightly trim the compression rings in length for the right gap in the cylinder bore. More importantly, the oil ring was impossible to fit in its groove.

Does anyone here know this FZ60130 kit?
Does anyone know where I could find genuine +0.03 rings?
If not, does it make sense to only change the compression rings and keep the old oil rings?

Thanks in advance for helping.

[Philippe-J.]

Thank you to Boris, who pm-ed me the precious info: there is a company in France, called THN France, who have a large panel of rings.
Among them, I found what is needed for my 4.2L engine with 0.03" oversize. It will need a light trimming of the pistons grooves, but it is the only solution I found to prevent me from completely changing the pistons and reboring the sleeves to the last oversize. Let alone resleeving to standard size.

As far as I can see, THN have an antenna in the Netherlands too.