A/C box to firewall sealant...What to use??

I just put the 70 Skylark body I have back on a good frame and have been tackling some of the other projects that go along with it.This will be a daily driver,so correctness isn't really going to matter.I am going to change the interior color as well as the vinyl top color,so you see where I am going.My questioin is,what can I use to reseal the box to the firewall with?I was considering just using silicone and let it dry but,I thought that I would get some opinions first.I want to do this this weekend and want to get it done before I put the 350 motor in it.I have no walkaway on it so moving around it will be no problem.
Thanks,Pat

 

Check here

Seam Sealer

Just used it for heater core re & re.

Good stuff.

 

Pat
3M makes a black rope type caulk to seal the firewall. If you want you could also use Mortite rope caulk. I would not reccomend using silicone since it might be difficult to remove.

Dave

 

Thanks Guys,
Looks like I will be making a trip to the parts store after work tomorrow.