First of all, Pleeeez use some periods!!
Simple answer....
If your amp is drawing more than 60 amps, your distro block fuse would blow. So it isnt that fuse that is limiting your amp. The limit to your amp might be in the size of the power wire. That amp is going to take some serious current, and your main power wire may not be up to it. If you upgrade your power wire, (and ground wire) and the distro fuse blows, then you will need a bigger fuse.
What is the light on your amp for? Is it just a signal light or is it an overload light?
And just because the amp has 90 amps of fuse protection, doesnt mean it is going to be always drawing that much current. Under normal use, it wont even draw close to that.