If you have an old Allstate from the 1950s or 60s, you will notice that the front end lacks a damper. It has only a spring (see photo below) and as such, this allows for a rather bouncy ride. Some call it the "pogo effect" and rightly so. When I dug out my old 1963 Allstate from my back garage where it had been sitting for 35 years, I noticed how unstable the front end was with just the spring.
I decided to replace the original spring with a new one and chose the Stoffis spring. I used a Stoffis 155 mm spring primarily for the quality, durability, and ride. They are 20% stiffer and 33% stronger than the OEM Piaggio spring. They are superior to the heavy duty springs available on some scooter parts sites. Getting the correct length (155 mm) was very important and made installation easy. Cost was around $45.
Once installed (see photo below), I noticed a much firmer front end the the "pogo effect" was gone. The bike handled very well and the Stoffis spring was a huge improvement. I would highly recommend those with old Allstate bikes to replace the original spring with a new Stoffis spring. You will keep the Allstate in its original condition and improve the ride and handling immensely.
Note: I later went on and added a damper to my Allstate front end (see photo below) and have posted my font end upgrade and costs on this forum in the past.
Allstate Front Fork Modification - Summary and Cost Estimate