It would be useful to know the specific rate for the new spring. If you visit
http://www.racetech.com you can enter your, bike, all-up weight, and riding style and it will suggest the correct shock spring rate. The following comments apply the 1983 CR480R and I know that Honda was making subtle changes to the shock and linkage during this time. You may be told that there are not after-market heavier springs available. However I learned that there is a range of Eibach springs 883.00XX.1 which are 55mm x 273mm in size. These are not specifically for the CR480R but they fit just fine. I am running a 883.0067.1 which is .67kg/mm. I am still playing with the sag, but can get in the ball-park with almost no pre-load. The .44kg/mm spring that came stock with the bike had the pre-load cranked all the way down. The other tip I'll pass on is that the damping needs work and Tru Technologies is the place to go. Rich Truinski - the owner - has a rocket-ship CR480R that runs in SoCal historic events.