Looks like what you have is a 58-62 261. That's what 3659365 translates to, and it has the bulge in the side of the oil pan mounting to clear the oil pump. Also looks like it has the captains bars just above and to the right of the block casting number.

Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.