Slant 6/904 flex plate no longer fits on new motor

I recently bought a new block and turbo setup off Gilbert titan a member of this forum. My og block had cracked so I bought a new block and put it all together along with dutras Aussie Intake and ct26 turbo. I went to bolt my rebuilt 1964 A904 3 speed onto this newer block but the flex plate is around a 1/4 inch too short in diameter to fit over the crank. The new motor I bought had a manual trans and I removed the pilot bearing and thought it would bolt right up, but nope. Will take any suggestions cannot just widen the hole on my flex plate cause it would get rid of the shoulder, is this a part I could find? or should I see if any trans shops can build me a flex plate that would work? I believe I posted this in the correct section please inform me if I’m wrong I’m not on here all too often. Any help is appreciated.

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