Help Please! At Wit's End with decode

[56pickup0]

Hoping someone will help me with a SBC decode. Just pulled from my 56 Stepside and these are the only numbers I can find.

Serial Number stamped on passenger side front corner of block.

355809F56A

Casting number at back of block

3970014

I've already traced the casting number to 70-74 350 2 or 4 bolt main.

Any help appreciated.
56pickup0

 

[hurst01]

56pickup0,

Yes, you are correct on the casting number. What is it that is driving you to wits end? Once you have the year and cubic inch, unless you are trying to decide whether the engine came from from an exotic build and is worth a fortune, what are you trying to find out? In my process of building an engine, what it came from is of no concern to me because ALL if the internals are exactly the same for a 350 Chevrolet engine from 1968 up to the year of late 86 (partial) which had roller cam and lifters. Even some 87 models didn't have them. The exception would be if it was a high performance with high compression ratio.
The DZ blocks were worth more, and possibly the early 283 cubic inch with factory fuel injection is worth more for someone trying to put it in an original car. I went through my information trying to find the numbers you mention on the front pad and I don't have anything on it.
Please don't be a stranger, if you can help answer any questions for anyone else, jump in there and help out.