I have always had success with Loctite 515 gasket maker .You do not need a gasket and it replaces the gasket . Perfect preparation gets perfect results .
Mark the oil seal housing before removal so it will go back on the same way it came off .As for the crank seal , leave the old seal in the oil seal housing and try sliding/installing the housing onto the rear of the engine .Use a small paper clip unfolded to where there is only one loop . Use this to help work the seal over the end of the c/shaft . When you get good and feel confident , install the new seal into the housing
.Clean everything and get ready ! Use a seal installer or a good substitute to make sure the seal is installed square and flat .515 [ not too much , just enough ] on the mating surface , lightly oil the seal / c/shaft seal surface and install . IDK if this plate has a dowel pin for alignment .
I use to use liquid Teflon sealer on small block Chevy head bolts since the threaded holes went directly into the coolant . I would use a USB ( shouldered ) bolt instead of the factory fastener .
Good luck .