Tips on how do I find my original 340 block?

Can anyone help find or give me some pointers on how to find my original block?

It's a 340 block. VIN #409210. I think the car used to be owned by a guy named Doug Fletcher in Kelowna, BC, Canada who has since passed away (only months ago). It was then bought by a guy named Mo (in Surrey, BC where I am as well), who I bought it from. I believe the car was originally B3. It's now B5. Any ideas?? Trying to track down Doug Fletcher's family is already super tough.

Any help would be appreciated! Thanks!

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