No you most likely cannot add enough preload. I’ll tell you why.
The scooter contra is short compared to other moby style springs. You will coilbind the spring much before you get to full variation. That’s why I suggested to use a stronger spring.
I battled with lack of variation on my moby and it all came down to the coils bumping into each other before the engine was done variating, leaving a lot of top speed unavailable. If top speed isn’t an issue than nbd. But yeah, Unless you use close to the full length of the scooter contra, you’ll coilbind before even getting close to full variation.