you can buy the belts different size stretchy belts to. so I don't think you'd need to change the compressor?
I fought thru the belts on my c6. proper annoying. Google around and holy crap, it's a ls thing. there's a 100 page thread on a gto board. once it starts it doesn't stop on its own. the older sports cars had a upper idler pulley which seemed to help. there was a company that made add on one years ago but I emailed them and wouldn't make any.
after a good 6 months of trying things, including a Lazer belt alignment tool made by gates, I didn't get it. I got a go pro video of it. a kinda non car guy friend of mine saw the video, commented the belt wasn't centers on the crank pulley. I'm like sure it is, what are you looking at?
long story short, I got to looking and he was right. damn compressor wasn't aligned right. there's no adjustments, it just bolts to the block and over 100k miles of hard use never a issue. but once it did it, it kept doing it. I could toss it on demand. 2 new oem tensioners, different belts, nothing. in the end a old school starter shim put under both rear bolts, belt centered up on the crank pulley and never threw it again.
I got nothing.. my only theory is core shift in the block.
I honestly didn't see it at first, it was towards the front of the pulley in this Pic. once shimmer up it ran even on both sides and never have had a issue since. beat the crap out of it trying.
here's it rolling off.