Hi Mick - I also have a 292 (complete engine, 'runner' ; from a 1ton chevy flat-bed : year was about 75 - 78 ? ) .
I bought this engine , and got too hear it running (if that means anything), plus , it also has a 'rebuild tag on one side' , of the block. I think , I'd use this engine , but it also has some 250ci parts installed.
The water pump = is not the 292 pump , nor is the 'intake & exhaust' , (those are looking just like my 250ci , in my 69 Nova. (my Nova engine IS the factory 'numbers engine' . . thus, I trust it more.
I did / have tried too find more info , for the 292 (Hecto in Mexico) . My block casting number is : 93406004 (I was told = year 75 - 84) . The date casting number (does make more sense , B 23 81 (Feb 23 , 1981) ?
This engine does have the engine ID number , on the dist pad - - but, who knows , what that means = M B 12594 ? ? ?
Then, I also had heard the "saying" , The Mexican Blocks were made better - - (but, that's only 'hear-say, I think' ) .
Could there be more info , about how too I D these engines - - I've (kinda) been looking , for more / better info (for about 10 yrs.) . . . and 'nothing' .
I really like what your are doing , and try too follow along . . . . keep going .
jim
Chino Valley , Arizona