Leaf Springs for C30 with Dana 70HD

[Aruba1]

I currently have a 1972 C20 upgraded to C30 with an LS engine and an NV4500 transmission. All corners have been updates with hubs, brakes and differential of a 1989 or 1998 C3500 pickup. The current leaf springs is a 4 plus 1 spring and it's too soft the empty steel bed. I need something stronger.

I plan to do some heavy towing. Will the DAYTON 22419HD (4100 lb) be an overkill or should I opt for the DAYTON 22419 (3390 lb)? Is the weighted rate per side or for both sides together? I already have 5000 lb air bags but I can't rely just on the air bags to carry all that weight.

Thanks!!