EDIT: Never mind, after posting this I realized I had a spelling mistake. None the less, here's a spy script that changes your sensitivity to 1.75, FOV to 75, and viewmodel off after shooting the first bullet with your primary weapon and works with quickswitch. This all resets by swapping weapons, pressing M2, or pressing 1 again. Note that it doesn't work if you use the scroll wheel to change to the primary weapon

I'm not too familiar with how the scripts work, and after finally combining two spy scripts others had posted, I ended up with this which works to my likeing.

Put this in your Spy.cfg

    //Replace Keybinds for the sapper/knife/revolver/watch/quickswitch

    bind "2"  equip_sap       
    bind "3"  equip_knife     
    bind "1"  equip_amby     
    bind "mouse2" " watch;spec_prev"         
    bind "q" "switcher"


   //RE-BIND M1//

    alias knife_vm_mode "bind mouse1  viewmodel_knife"
    alias amby_vm_mode "bind mouse1  viewmodel_amby"
    alias sap_vm_mode "bind mouse1  viewmodel_sap"

   //ATTACKING//
    alias  viewmodel_knife " attack;r_drawviewmodel 1;spec_next"
    alias -viewmodel_knife "-attack;r_drawviewmodel 1" 
    alias  viewmodel_amby " attack;r_drawviewmodel 0;sensitivity 1.75; fov_desired 75;spec_next"
    alias -viewmodel_amby "-attack;r_drawviewmodel 0;sensitivity 1.75; fov_desired 75" 
    alias  viewmodel_sap " attack;r_drawviewmodel 1;spec_next"
    alias -viewmodel_sap "-attack;r_drawviewmodel 1"

   //EQUIPING//

    alias equip_knife "slot3;r_drawviewmodel 1;knife_vm_mode;sensitivity 3;fov_desired 90"

    alias equip_knife2amby "equip_knife;alias switcher equip_amby2knife;bind 2 equip_sap2knife;bind 3 equip_knife;bind 1 equip_amby2knife"
    alias equip_knife2sap "equip_knife;alias switcher equip_sap2knife;bind 2 equip_sap2knife;bind 3 equip_knife;bind 1 equip_amby2knife"

    alias equip_amby "slot1;r_drawviewmodel 1;amby_vm_mode;sensitivity 3;fov_desired 90"

    alias equip_amby2sap "equip_amby;alias switcher equip_sap2amby;bind 2 equip_sap2amby;bind 3 equip_knife2amby;bind 1 equip_amby"
    alias equip_amby2knife "equip_amby;alias switcher equip_knife2amby;bind 2 equip_sap2amby;bind 3 equip_knife2amby;bind 1 equip_amby"

    alias equip_sap "slot2;r_drawviewmodel 1;sap_vm_mode;sensitivity 3;fov_desired 90"

    alias equip_sap2knife "equip_sap;alias switcher equip_knife2sap;bind 2 equip_sap;bind 3 equip_knife2sap;bind 1 equip_amby2sap"
    alias equip_sap2amby "equip_sap;alias switcher equip_amby2sap;bind 2 equip_sap;bind 3 equip_knife2sap;bind 1 equip_amby2sap"

    alias  watch " attack2;r_drawviewmodel 1;sensitivity 3;fov_desired 90" 
    alias -watch "-attack2;r_drawviewmodel 1;sensitivity 3;fov_desired 90" 

    equip_knife2amby 

What I can't seem to prevent from carrying over is my sensitivity dropping to 1.75, viewmodel turning off, and FOV turning to 75 when I attack with my primary weapon after pressing 1 or Q. I've tried some variations of this script in my autoexec.cfg, but can't seem to get it right. Because of this problem, I've stuck to just playing spy for the last two days.

Save this as a new .cfg file called default

    developer 1
echo "default settings loaded"
developer 0

// viewmodel/combination script binds
bind "0" "slot10"
bind "1" "slot1"
bind "2" "slot2"
bind "3" "slot3"
bind "4" "slot4"
bind "q" "lastinv"

bind "mouse1" " attack"
bind "mouse2" " attack2"

Finally type "exec default.cfg" into each class .cfg file you do not want this script to carry over to