Hmmm...Has Rivergate put out multiple versions of their seal design? I just installed mine last week. The kit was purchased several years ago, but I was not provided a new piece to bolt to the block above the rear main cap as Hap has described above. My understanding is you use the stock piece thus maintaing the original scroll seal.
I'm an amature at this stuff, but my understanding of RG's system is as follows:
The seal bolts to the rear of the new engine plate and the seal edge seals around the flange where the flywheel bolts. (This surface was not designed for a seal and any flaws could negate any benefits.)
The silicone serves two purposes per RG's instructions. First it replaces the gasket normally found bewteen the block and stock engine plate to seal better and "provide uniform thickness". Second, and this is the big iffy part in my opinion, you are suppose to fill the void between the block and new engine plate, being sure to fill the joint towards the bottom edge of the void. I don't have the instructions in front of me, but I think they specifically tell you not to build the silicone up onto the crankshaft or crankshaft flange.
In theory, any oil leak coming through the stock "scroll" seal will get trapped in the void between the block and the new seal. So I don't understand is how the RG seal can make a leak worse with the possible exception the gobs of silicone failing at any place it is suppose to seal between the engine block and rear plate.
Oh well, we'll see if I have to pull the engine out later. This is my first rebuild, so if the darn thing starts, I'll be happy.
Allen