I have a low mileage 99 k2500 suburban with the 7.4.

Is there a dedicated great chevy forum for info??

I’d like to do some beefing up the suspension. Not really concerned about adding height but heavier duty shocks front and rear. Maybe beef up the steering. Etc

I've owned my 2008 2500 for 8 years.  Unfortunately, in all of my time on the internet, the absolute best group I found was on Facebook, the 2500 Suburban Owners group.  Lots of great info, and it's a large group.  I dumped FB recently, so that was part of the collateral damage.  

I've not had much luck finding other groups/websites.  There are some, but on those I find myself giving information more than I get, which is fine, but I also like to read others' experiences with their 2500 trucks.

ETA: The two favorite shocks are the Bilstein 4600/5100, and Fox.  4600 for stock height, 5100 for lifted trucks.  I've had 4600s on mine for 7 years and 100k miles - lots of heavy (8600 lb) towing, too - and they're still doing great.

Regarding front suspension/steering bits, Kryptonite was generally held in high regard and recommended.

There’s not a chevy forum anywhere? I know there’s several for Ford trucks that have categories for each model,, 150, 250, etc

I've got a 99' GMC K-3500, same body style, bought it new in 99 and it's got 220,000+ miles.  The crew-cabs, tahoes, and suburbans kept that body style until 2001.

I always go here for good advice: https://www.gmt400.com/

I have a diesel suburban and Diesel Place seemed to be a pretty good site. They have info on stuff besides the diesel engines.

Options on beefing up the suspension?

There isn't much out there, except a full lift-kit or a solid axle swap.  WFO concepts has some beefy options, but you better have deep pockets when you start looking for Dana 60 Axles.
https://www.wfoconcepts.com/cr/Chevy-88-98/9105/9463