You're only changing the crown and pinion, not the LSD (centre) but you will need to set it correctly otherwise the diff will whine and wear. I would recommend taking it to a diff shop to set up.
You may be better off getting two carriers, and set one up with your LSD and fully sik drift ratio and another with a cheap open centre and more highway friendly gearing. If you've got a zenki rear end you could get a spare carrier off an old celica.