The spring and follower you chose will work fine as long as it is mil-spec and going in a mil spec mag. I have been using ASC stainless mags and have good luck with them not causing problems. I know my FN2000 is picky about the type of mags it likes. No cheapo mags for that gun.
I emailed FN yesterday and asked if they had stopped making the FN2000 after I noticed there are few if any new one for sale. According to them they are "Out of stock and do not expect to have any more for at least two years." I think they are focusing on the new F-15 rifle and have side lined the FN2000. Some dealers I talked with think that they may not bring the FN2000 back at all for the public market. If that is the case our FN2000 will go up in value as time passes. I have noticed that the ones for sale on Gunbroker are moving up in price. Does anyone else have info on the subject?
FS2000 Gen 1
PS90-SBR Gen 2
FN HP SFS
FN Model 1905/1906
(MM's #3860084010, #3860084030, #3810084020, #3480084020)