Flex plate for 5.9 and 904

I have the same question but a slightly different issue. I had a custom torque converter built and the Magnum flex plate will not work.
The lip on the factory flex plate contacts the converter out by the ring gear before the mounting tabs contact at the attachment points.
The new attaching bolt holes are slightly smaller diameter than the converter bolts provided. Yes I can drill them out.I

I bought a used B&M SFI flex plate #10239 not realizing that this is for an LA/904. Won't work on 5.9 Magnum/904. The correct B&M 10241 was discontinued long ago.
Any ideas?