adding public ip (transparent) to a cisco 1721 with existing nat config

I have an existing cisco-config with NAT (see below) , and I need to add a public ip to a vpn-firewall-device behind the cisco . I still need the NAT on the existing public ip .
The existing fixed ip is auto-assigned .

version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname <alpha>
!
boot-start-marker
boot-end-marker
!
enable secret <pass>
enable password <pass>
!
no aaa new-model
!
resource policy
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
ip subnet-zero
no ip source-route
!
!
no ip dhcp use vrf connected
ip dhcp excluded-address 10.0.0.1 10.0.0.99
!
ip dhcp pool LAN
   network 10.0.0.0 255.255.255.0
   default-router 10.0.0.1
   dns-server 195.238.2.21 195.238.2.22
!
ip dhcp pool lan
!
!
ip cef
no ip domain lookup
ip name-server 195.238.2.21
ip name-server 195.238.2.22
!
!
interface ATM0
 no ip address
 load-interval 30
 shutdown
 no atm ilmi-keepalive
 dsl operating-mode auto
 pvc 0/35
  encapsulation aal5mux ppp dialer
  dialer pool-member 1
!
!
interface FastEthernet0
 ip address 10.0.0.1 255.255.255.0
 ip nat inside
 ip virtual-reassembly
 shutdown
 speed auto
 full-duplex
 no cdp enable
!
interface Dialer0
 ip address negotiated
 ip access-group 150 in
 ip nat outside
 ip virtual-reassembly
 encapsulation ppp
 dialer pool 1
 dialer-group 1
 ppp authentication chap callin
 ppp chap hostname <user>@<isp>
 ppp chap password <pass>
!
ip classless
ip default-network 0.0.0.0
ip route 0.0.0.0 0.0.0.0 Dialer0
ip route 127.0.0.0 255.0.0.0 Null0
ip route 172.16.0.0 255.240.0.0 Null0
ip route 192.168.0.0 255.255.0.0 Null0
ip http server
ip http access-class 2
!
ip nat inside source list 1 interface Dialer0 overload
ip nat inside source static tcp 10.0.0.2 80 interface Dialer0 80
ip nat inside source static tcp 10.0.0.2 25 interface Dialer0 25
!
access-list 1 permit any
access-list 2 permit 10.0.0.0 0.0.0.255
access-list 2 deny   any
access-list 150 deny   ip 127.0.0.0 0.255.255.255 any
access-list 150 deny   ip 172.16.0.0 0.15.255.255 any
access-list 150 deny   ip 192.168.0.0 0.0.255.255 any
access-list 150 permit ip any any
dialer-list 1 protocol ip permit
!
control-plane
!
!
line con 0
 exec-timeout 0 0
line aux 0
line vty 0 4
 password <pass>
 login
!
no process cpu extended
no process cpu autoprofile hog
sntp server <sntpserver>
end