I owned an S&S design from that era.it tended to develop a lot of weather helm pretty quickly with changes in wind speed. You could pretty easily balance the helm by depowering the mainsail, but it was important that the main sail was not blown out. So question one would be, what is the condition of your sails?
My boat came with two mainsails, one almost new and one that was blown out. I mostly used the new main, but I used the blown out main while the good main was being worked on an the boat had a lot of weather helm that sail adjustment alone could not help.
These boats were also very sensitive to having the right Genoa up for the windspeed. We typically sailed with a 155% Genoa but needed to change headsails down to the 140 around 12 knots, reef around 15 knots, and go to the 125 around 18 knots of wind.
When I'm tuning a rig and don't have a "recommended" amount of rake for guidance, I rake the mast at between 3-5", depending on the size of the boat, and then sail the boat in 10-12 kts wind, and take notice of the amount of weather helm. If the weather helm is too light, I'll tilt the rig back a bit more. If it's too heavy, I'll tilt it forward a bit. My preference is for a somewhat lighter weather helm. As I see it, tuning the rig gets the amount of weather helm within an acceptable general range. Trimming the sails fine tunes the amount of weather helm.
I'm not familiar with that boat, but 8" rake sounds like a lot. I had a 25' boat that made me seriously arm-weary to steer it in a breeze, and discovered that a 3" extension had been placed in the forestay and the mast had been raked back too much. I removed the extension and tilted the mast forward until it had a comfortable weather helm when I sailed it. That resulted in a light weather helm and, in one design racing, the boat was competitive with the best of the competition.
Regardless of the "recommended" amount of rake, I adjust the mast rake to achieve a comfortable weather helm and to optimize speed and pointing when closehauled.
I'd suggest you adjust the rake to 4" and see if that lightens the helm. If it doesn't help, you can always put it back.