I'm not overly worried about more power. I don't EVER put my foot to the floor, and it's rare I put my foot IN it. Seriously, it's not a hotrod machine to me, it'll drink gas like an alcoholic and I've got a 370Z for my "I wanna have fun driving" days.
Do I NEED to get a whole rebuild or replacement? No, I don't, but I really don't feel comfortable with a top-half rebuild and a 275k lower end and transmission. Not in a vehicle I'm going to be doing family vacations 1000 miles or more from home. Maybe it's silly, I don't know, but it's just a comfort level thing for me. For this vehicle, reliability and comfort is much more important than performance.
Guy just trailered it off... he's gonna talk to his rebuilder and get a 'ballpark' for the rebuild. My main concern with the LM7 swapout (this is an L59) is a tiny bit of loss in power. Not much, but ~20HP might very well make it feel a bit anemic - especially since I have 3 alternators which already will sap a bit of power. I think the transmission rebuild for a grand is probably fine, don't need to spend $1600 on a factory reman - the warranty is one thing, but honestly, if something like the motor or trans is gonna crater, I'd expect it in the first few thousand miles or month or three.