I bought 2458 without confirmation one way or the other that the engine was original. The seller didn't specify and I didn't press it to keep the price down. Turns out two owners ago the engine number tag on driver's side was painted over and the seller either didn't care or thought it non-original so left it painted for over 30 years.
As I've been pawing over the car and a few boxes of parts I found the original engine id tag still attached to the intake manifold, which was good confirmation that little has been molested (Edelbrock intake and Holley carb now) and replaced parts have been saved and boxed up.
Today I took a heat gun to the engine id tag and with a little heat was able to wipe off the thick soft paint. It was easier than I thought it would be. I have updated my registry information to show that the engine is original #1535. I guess I can see it in the block now, but without the tag I just couldn't quite make it out. It was a good guess at best. It's nice when two clues corroborate each other.