Hi and welcome.

It would help to know which kit you've got for a start!

Some of the pickup routs are a bit on the tight side. I normally use a small sanding drum on a Dremel to enlarge them a bit to get the pickup sitting happily in the middle of the rout without being angled because it touches the sides.

Humbucker pickup springs are normally a standard size, so shouldn't be too long. Unless this is a bass and teh springs go underneath the pickups, in which case they may be a bit on the long side.

So it really helps us to know what your building, and pictures help!