On the 2010 MTFCA site there's a posting called "Hogs Head Felt" dated Jan. 15th. 2010. About 3 million opinions listed there but perhaps you can firure out what's best for you.
Lay a 3/8" bead of silicone on the block shelf and discard the gasket. Let the sealant skin over a few minutes before setting the cover down. I have built a few early T's and found this to be highly effective given the tolerance variations common to these engines. Also there are problems with many of the reproduction squre hole trans covers. As always, there will be other opinions but this has worked well for me.
Erik
The point might be moot now if you're done the job already but further checking seems to indicate that a problem can develop with the 4th. main top bolts coming out of alignment by using or not using a gasket. Prehaps a dry fit and checking the bolt alignment is in order.