Rebuilding with #matching ??

[Gator70]

I have a dilemma, I have a 2nd owner 70 K15 GMC, the truck only has 60K on it but needs some tlc. I am stuck between rebuilding the stock motor/tranny to keep all of the original #'s together, or dropping in a crate rebuild. I wont be selling this truck or making it a trailer queen, but will be making it very pleasing to the eye. I like the sentimental value of having all the original parts kept with the truck, i was also told by my grandad(original owner) that the motor is a stock 300hp 350. Have not dug into the block # but the head # didnt show anything fancy. The block was produced Aug/69 by the stamp on the front.

I am also changing the front brakes from drum to disc and am wrestling with the same situation(change out whole front end vs modifing original)

Any thoughts??