That chip looks interesting.
I was going to suggest using a TDA7000 with a 10.7MHz IF.
It's a common chip that you can buy for a couple of dollars. It needs a few extra external components but it's easy to set up.
You can even buy a kit from jaycar which has everything you need ready to go, all you need to do is change the tuning coil for the lower 10.7MHz IF.

Interfacing it into the radio is not particularly hard either. Again, you'll still need the radio circuit diagram.
The FM demod board is constantly running and the IF is taken from the 10.7MHz IF buffer amp output.
If you want FM, then just switch the audio amp's input from the AM/SSB detector to the FM board.

For transmit mod, the radio is put into AM mode. The audio removed from the high level modulator and it's held ON.
The audio drive is then applied to the VCO in the PLL loop. Picking the right place and method to inject the audio without effecting the VCO will take a little bit of consideration.

i know this is a old post but as a operator/owner of the now ex Christchurch nz link i have a few words
first the link was great...in Christchurch at the time ..well before the quakes hit in 2010 it was a blast to use.....unfortunately the powers that be here in nz stopped it stone cold in its tracks when another operator in the north island got raided for having a linked station using this system that "packet cb""has.
second in the recent rule changes made in nz to the uhf cb band a few submissions went in asking for the system of linking via the internet be allowed....as usual the "powers that be"  stopped that in its tracks with some cr*p that it defeats the "use" of uhf cb...what a pack of c**ks!...
anyway i now live a lot father north of Christchurch now and things have changed here in nz as of recent so much so that there is only two radio inspectors for the north  island and one for the south island...in the area i now live there is only 3 operators for about 100kms and we all agree that time to put another link up..."packet cb" has been running the system from his site for q number of years now and i still login via the net to the links to talk all over the world to operators in other countries .....to note my neighbors brother is the north island radio inspector..and he sits out side my place (i live on a hill) to monitor for illegal fm radio station pirates when he is in town....fi**en funny as! 
http://palmbeach.dynalias.com/gateway.htm

as a foot note i know you guys have issues on your uhf cb radio repeaters over there (been reading up on the ch7 saga)...in Christchurch (ch1-31)its run by a neo-nazi wannabe racist f**kwit and the so called nsdap skinhead dicks....if they only knew the "owner" known sex offender he would be in their dream of a death camp!

hi all first post so forgive me if i get it wrong
ok we have a large collection of rigs already ...see the list!

Stoner PRO-40 40ch ssb

Siltronix 1011c 10 meter plus cb am/ssb

Cobra 139xlr 40ch,am/ssb

Courier centurion 23ch am/ssb

Courier centurion  40D 40ch am/ssb

 Royce 1-641 23ch, am/ssb

Royce 1-642 40ch, am/ssb

 Dak-X 40ch, am/ssb

 Tram D-201 early hardwired 23ch, am/ssb

Tran D-201 late 23ch, am/ssb

Tram D-201-A 40ch, am/ssb

Tram D-300 40ch am/ssb

Hygain VIII 40ch am/ssb

Colt black Shadow 40ch am/ssb

Realistic TRC-490 40ch am/ssb

Realistic TRC-55 23ch  am

2x Stalker XX export 80ch am/fm/ssb

Stabo XF8092 ProII 10 meter am/fm/ssb

Superstar SS-4900 10 meter am/fm/ssb

Cobra 2010gtl 40ch am/ssb

Browning MK III 23ch am/ssb

Robyn 520d 40ch am/ssb

SBE Land command LCBS-4 40ch am/ssb

SBE Console MK-VI

Communications Power Cpi 2000

Arf-2001

Superstar 7000DX

now none of these are for sale at any price!
but we need more!..and also after accessories for the above radios..as an example the station console for a cpi2000.etc etc

why do we want these...both myself  (Mike ssl100) and David (91dd018 of jarkata) are setting up a radio museum at our shop here in nz so when customers come in they can look at and get on air with these radios in store...all of the above radios have been put back to stock form and in some cases repaired
see what you have in the cupboard and pm me with what you have.
we are also after parts rigs so again pm me and we can come to a deal.
the shop is at http://www.yeticomnz.com
some of the rigs are on our youtube site here http://www.youtube.com/channel/UCY43qsuHQuhrC_yJCPFXdcw?feature=mhee you may be lucky and hear your own voice on the channel!
thanks in advance for viewing...mike

Well i wish i could find something possitive about it but i cant so down the shit shoot with it or a dam good wheel chock for my car or a truck hahaha a stepping stone for the demented that all it is or maybe a meeting place for  sydney dole bludgers inc. 

I've heard it all now, JD saying Rocket smells hahaha pot... kettle.. BLACK!