Help Decoding a Small Block

[Chan-man]

I have a 1976 GMC Royal Sierra 1500 Long Bed. It’s more of a Frankenstein truck as it has Chevy door panels and what I believe to be a 78 carb. My issue is I went to replace the carb and a 1976 edelbrock isn’t fitting properly. I’m now wondering if the intake has been swapped or the entire engine. If it has been swapped then what type of engine and what year is actually in my truck. I took a picture of the engine code as best I could tonight and am attaching it but haven’t been able to find the vin on the block yet. Any help is appreciated and will look for any codes I can if I’m told where to look.
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