Glad to see another MGB owner crossed over. If you still have an MGB (I do), it's a trick to switch between the two. Pedal placement and (of course) gearshift operation are so totally different. I can't say which I prefer. The MG is perhaps more fun in town, but the 912 is a much better highway ride. Mine is a 67 soft window Targa and, even with the top and rear window down, it's much more civilized at speed than the MG.
One big difference between MG's and 912's is that there's comparatively little mechanical literature for the 912 that's affordable. There's no Bentley reproduction of the factory repair manual available for $45 as there is for the MG. Porsche factory manuals are expensive.
Earlier posts mentioned the California 912 websites as good resources. Also, be sure to check Dave Hillman's 912 website at
www.hillmanimages.com/912. Dave has done a splendid job of documenting a lot of 912 repair operations, and his photo illustrations are extremely helpful.