<VV> carb float assist spring stiffness

[rbkj84 at comcast.net]

To the carburetologists out there:

I was working on my carb (well one of them) yesterday.  Had reason to believe that the float level 
needed to be adjusted.  I had ordered a few parts from one of our major vendors 
to have at the ready.  I replaced the carb float axle pin (the new one appears 
to be brass), reset the float level and float drop and noticed that the new 
spring I was intending to install seemed stiffer than the old one.  I presumed 
that the old spring (how many years old I can't begin to guess) would be less 
stiff due to age.  But when I put the new assist spring in, and held the top part of the carb in the normal position to check for the float drop, the float would not bottom out against the tang.  I put the old one in and it bottomed fine but the spring assist was clearly still there.  I went back and forth between the two springs trying to figure it out.  With the new spring, when I forced some air under low pressure into the inlet, the flow was restricted.  Not sure how much pressure the fuel pump puts out and the pressure at the level of the inlet into the carb.  Well, I decided to go with the old spring to get full drop.  Buttoned it all back up and it seems to be fine.
Question:  should the float bottom out when held in to regular position in the air to check the drop?
Also, I had recently put in a new main carb gasket in that carburetor about a year ago or so.  It was also from a major vendor.  But the one that I put in yesterday from another vendor was about 50% thicker than the other (not due to compression from use).  The thicker gasket seems to have snugged down better and my guess is that it will seal better than the other one.  Is there a rule of thumb for gasket thickness?  Again, both premium gaskets from top Corvair vendors.  Does size (thickness) matter?
Thanks for your responses to my questions,
Regards
Ron
64 Spyder
65 Corsa
91 Buick Reatta
soon to purchase 4 post lift for the garage !!!!!! (oh a happy day !!)