I recently had some misfortune with my 427 in my chevelle. A valve broke and destroyed the head and piston. It had 049 heads with 2.19s 1.88 with bowl blending. 11.5 to 1 compression.
Going rebuild it. 14 to 1 compression and I have a pair of 990 heads I’d like to use. My 427 with be 60 over now so it’ll be a 439 ci now. Will the 990 be too big for my 427 planning revving it to 7500 vs 6800 with the 049s. Cam is 263/271 @.630 1obe sep. solid tappet.
Just looking for some input if these 990 would work good or not

They will work.

I ran the 990 heads for years on my 427 back in the day.
Ran high 8's with them in my Corvette.

I've had great luck with 990 heads on 454's , never had a 427 though. I've gone from ovals to 990's and always ran faster even in 3500+ lb cars.

I think you'll be happy.