I spoke with PIM and they recommended deleting the long spring around the pushrod, and re-using the smaller new boot that came with their m/c.
I did find some Alfa 115 m/c rebuild kits on eBay from an Alfa store that looked like they had a long enough dust boot to cover the long spring but a little pricey at $45, for what it is.
Still curious if anyone knows what the purpose of the long spring is on the m/c if anyone knows.
Thanks,
Shashi