calling Mr Holley!Help

[67chevemall]

Alright so this carb rebuild stuff is kind of fun?
I have a 4150\60(still can't tell the difference?)
on the go!

I'm just about to put it all together again but need to know about the jets I
have??????

I have the 4 jets two say #642
and two say #65

Which ones would be primary and which ones secondary?
How does the numbering work with jets??????????????????
bigger the # the bigger the hole????????????????????????????
Cheers and thanks