Aluminum versus iron when buying used LS

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I've started to look for an LS for my 65 GMC and while I had been leaning towards an iron block Gen IV 6.0 such as the LY6 or L96, I keep seeing running, high-mileage Escalades and Denalis around my area with the 6.2 aluminum L92 for a decent price for the entire vehicle. My initial thought is that I could part it out after taking everything I want.

With either engine, I'm really only interested in the block, crank and heads and the plan is a complete rebuild. So my question is, should I be looking at these? Could the ability to hear them running or performing a compression test help with the decision?

My guess is that the inability to bore the aluminum blocks makes these higher mileage less attractive than a higher mileage iron block. I have no interest in sleeving a block.

I am still weighing the pros and cons of a full rebuild versus a crate engine though.

Thanks!