I had a similar issue with a Tough Traveler Expedition/Mt.Santononi pack years ago. I scored some stainless rod of 5/16" diameter and bent it to shape over my anvil with a medium hammer.
The frame was never too successful as I could not optimize the bends. The length too was difficult and I ended by grinding down the ends to fit.
The pack never rode right.
Eventually I got the firm to make me a new frame and the pack became functional. It was an early internal however and the suspension left a lot to be desired. By today's standard the hip-belt is downright primitive.
I suppose I could improve it with webbing and pads, but given my wealth of newer packs, I just do not do it. I use it now for gear storage.
Maybe I should make a red cover and convert it to my personal jump (i.e. major first aid) kit. Sentimentality makes me keep it.