another few things to watch out for and consider when changing the seal
when you remove the timing sprocket from the crank to access the seal be carefull about keeping eye on the keyway as its easy to loose, but n saying that they are usually seated into the crankshaft snugly and shouldnt pop out just sometimes they do.
when removing the seal with the oil pump in place and using a screwdriver take care not to damage the sealing surface on the crack when trying to get the blade in behind the seal.
and when installing the new seal use some grease (any type) to lube the sealing surface of the seal so that it slips onto the crankshaft nicely. its all too common where people oversee this and install the seal dry (no lube) and the sealing surface catches on the edge of the crank and turns inside out causing a catastrophic leak and you need to pull the whole lot to bits again and re do it all.
good luck with the job mate. should be plain sailing if you stick to the advice the boys here have given you
Ryan