Did you have the top of your block skimmed? The timing cover needs to be flush with the top of the block for the head gasket to seal properly. Best practice would be to have the cover and the block skimmed as a unit, as you can't be sure when mating parts from different engines. I'd worry more about that than what brand of sealant to use on the mating surfaces. See how closely they fit in this photo:

http://www.w124performance.com/images/OM602_head/block_surface2.jpg

If you mix and match parts, the fit isn't always so pretty.